Hilda

, full name, is a Demon that serves as both the adoptive mother and wet nurse to Beelzebub IV.

She is also the main female protagonist of the series.

Appearance
Hilda is an extremely beautiful young woman with glossy blonde hair that covers one side of her face and is usually tied in a bun, forest green eyes and has a large bust (on par, if not larger than her sister). Her clothes are mostly elegant and black with frills and white quillings, thus resembling elegant gothic lolita fashion.

She is seen wearing other outfits on a few occasions. One occasion being right after she wakes up, where she was wearing a modest pink nightgown with her hair down. In one chapter, she was shown wearing a yukata while playing with fireworks along with Lamia.

When she infiltrates Oga's current school she dresses in the Saint Ishiyama High uniform, though she complains that the shirt is "a little tight".

Hilda normally keeps her left eye covered. In Chapter 186, she reveals that it's not because her covered eye is weak, but because it's too strong and using both nauseates her. When Hilda removes the hair blocking it, it's revealed her left eye is a solid color and is capable of detecting things ten times faster than the normal eye and even see the tiniest object.

Personality
Hilda commonly displays a cold and impassive demeanor, a character trait that she breaks only on rare occasions such as her interactions with Beel. Towards Beel, she is very affectionate and protective, acting as the role of the mother and performing the task a mother would such as cooking for and bathing Beel. She often knows more about the current situation than any of the other protagonists and is easily able to manipulate others into doing what she sees best. Hilda also has a fondness for extremely spicy foods, such as super spicy habanero buns. She is shown to be just as bloodthirsty and violent as Oga, a trait that earned her the nickname "Oga's Bride" at Ishiyama. When fighting, she displays a complete confidence in her own skill and power, regarding her opponents calmly and often taunting them during the battle.

She enjoys teasing and tormenting Oga, frequently making snide remarks about his intelligence and (in her own mind) poor parenting skills. At the beginning of the series, she is openly disapproving of Oga as Beel's parent. After he defeats Hidetora Tōjō, she becomes much more accepting and warmer toward him, even thanking him afterward, though she still bickers with him. After spending some time with Oga and Baby Beel, it seems that her behavior has changed, as Izabella noted, and wonders what kind of human could be responsible for this change.

When she got amnesia, her personality became significantly more innocent. She no longer showed Oga any animosity, and it's even hinted that she has started to develop romantic feelings toward him (she blushes whenever she is near him). She also becomes noticeably kinder, showing a great deal more affection toward Beel, whom she called "Beelze" instead of "Young Master", and to Oga, whom she refers to by his first name, something only his family has done. This, however, did not completely extend to Furuichi, whom she almost instinctively feels to be nothing more than "a creepy douche", and she is still annoyed at Aoi Kunieda's presence, even thinking that Kunieda is Oga's "other woman". However, this personality vanished when Beel kissed Hilda, restoring her to normal.

Interestingly enough, this side made an unexpected return during the Santa Arc when Beel kissed her again. The shock somehow brought this side back. It's been implied that this person may be the repressed emotions of Hilda; when this person is seen, she indulges in her motherly side to Beel and treats Oga openly with affection, hinting that she may have romantic feelings that she usually represses.

History
Hilda and Yolda were always fighting for the top spot at the wet nurse training academy. She served Iris before Beel was born.

Tōhōshinki Arc
Himekawa, the second member of Tōhōshinki, planned to kidnap Hilda, who he and the rest of the delinquents believe to be Oga's wife, to attract him and take him out. He orders the Team Caras to bring her to him, and they bring her along with Furuichi. The change of plans makes Himekawa angry, and he decides to lure Oga out. When he asks for Hilda's phone and she said she didn't have one, he shoots her with Suzuki's acid gun to erode her dress, proving her statement to be true. Afterward, Furuichi gives Himekawa his own phone to call Oga.

Oga gets to Himekawa using Alaindelon. When he refuses to work for Himekawa, they fight and Himekawa is overpowered. He tries to make use of the hostages, but the effects of the drug Hilda was underwear off and she defeats his subordinates. Oga then knocks him out. After that, Hilda takes Oga's wrist to check the Zebul Spell, and Oga finds out that she got caught on purpose to measure Himekawa's strength. When Oga tells her that it wasn't only him but Baby Beel was worried about her, she replies that her master doesn't care for her; rather, he is only affected by Oga's anger. When Oga goes to give Beel to Aoi, Hilda meets her and tries to pick a fight with the Queen. Aoi is at first outraged at fighting Oga's bride, misunderstanding Hilda's role in Oga's life. Thinking that Beel was Hilda's son that she abandoned to Oga, Aoi violently rushed against the Demon Maidservant, but she was easily outmatched.

Later, when Baby Beel caught a fever, she was so worried about the child's health. Seeing Oga was showing no interest in Beel's situation, wondered if he could go more than 15 meters from him. She kicked him out of the house and disappeared. She came back when Oga also came back from his loss against Tōjō; she went to the demon world to bring a doctor, Furcas Rachmaninoff, and his assistant Lamia, to find out Beel's problem, but he was gone. So she stayed with the two of them when they tried to recreate the tie between Oga and the Demon Lord. She reappeared during Oga's rematch with Tōjō, to help her Master cope with his newly-found healthy condition.

Saint Ishiyama Academy Arc
Hilda transfers to Saint Ishiyama and shocked everyone with her arrival. Upon arguing with Kunieda regarding the seating arrangement, she already gained the fame of being the wife and Kunieda being the mistress. Hilda got seated in the chair next to Oga. When the class found out that the match between the Six Holy Knights and the Ishiyama delinquents was going to be volleyball, the whole class froze. Kunieda first tried to get everyone to practice but fails because Furuichi was the only one there, and that was just because of his perverted goals. Hilda, saying that her master really wanted to defeat the young man named Miki, agreed to be the one to make the other guys want to practice. The Red Tails were shocked and thought that Hilda would use the typical way of seducing the men, and were pretty unsure of her big declaration. They warned her that she would be a laughing stock if she wasn't triumphant over her words. Successfully leading the men into practicing through a sick and stupid joke of kidnapping them, she and Alaindelon manipulated the whole situation and made the girls' eyes widen in disbelief.

Hilda makes a proposition that anyone who can return her serves will be the captain. Because of the sheer strength and speed of the ball, everyone became intimidated until Kunieda volunteers to do it. At first, she was astounded because of the speed, saying that she did not even see a ball pass by. By the second serve, Hilda made a jump serve and made sure it was tougher than the last one. Kunieda returned the serve. Hilda decides that Kunieda will be the captain of the team, with Kunieda commenting on how it seems that that was Hilda's original intention from the very beginning.

Prince En Arc
When the battle between Oga and Kariya ends with a hole between the Human and Demon Worlds opening up on the roof of the gymnasium, Zenjurō Saotome goes up to fix it. Once he finishes fixing it, Hilda shows up, asking him if he was one of Behemoth's men. When they start fighting, he makes pervy comments about her underwear and harasses her by grabbing her breasts. Pushed by her anger, she releases her power, only for Saotome to cast a powerful spell that immobilizes her. She then notices that he is a Spell Master by the Zebul Emblem on the back of his hand.

Kunieda pulls Oga aside to ask him about what Beel and Hilda "actually" were, already suspicious about their true identities as demons. Oga tries to explain, but he can't remember Baby Beel's real name, which gets him upset. He crawls away crying, then bumps into a woman who looks like Hilda. This helps him to remember Beel's full name, Kaiser de Emperana Beelzebub IV and tells them that they shouldn't make the Demon Lord's child cry like that. As Furuichi calls the woman "Hilda", she approaches him and tells him not to put her together with that 'whore', and knocks him out. After that, she goes to Oga, declaring her love for him. She asks him if he could please die, and tries to kiss him. At that moment, the real Hilda falls from the sky in a lightning bolt, stopping the woman from kissing him. The woman is revealed to be Yolda, Hilda's sister, whom she fought against for the top spot in the wet nurse academy. Hilda tells them to go away, and that the woman was after her. Suddenly, two other nurses show up, telling Yolda to stop. They then reveal the existence of Beel's older brother, Lord En.

They go to Furuichi's house. The nurses explain that En was sent to the Human World to help Beel in his effort to destroy humanity. Hilda, Oga, Kunieda, and Beel return home together. Partway through, Kunieda splits from the group because her house is in the other way. She gets captured by Hecadoth, one of En's personal soldiers from his 34 Pillar Division. Hilda and Oga make a plan to rescue her. Oga distracts Hecadoth in order to make Hilda catch Kunieda. When Hilda successfully saves Kunieda and hands her to Oga, Hecadoth impales her. Hecadoth reveals that his real task was to disable Hilda. After Kunieda wakes up and sees what happened to Hilda, Oga tells her to look after Hilda for him while he fights Hecadoth, though he is no match for the Pillar in his current state. Then Saotome shows up and defeats the Pillar, who is then teleported along with the other two Pillars back to the Demon World. They take Hilda back to Oga's house, and Alaindelon brings Dr. Furcas and Lamia to take care of Hilda and Oga's injuries.

While Oga and Kunieda were training, Hilda recovered in a week's time. Furuichi, Lamia, and the gang were fighting Prince En through online gaming for three days to find out were his exact location was. When they went to buy food and drinks for the gang, Furuichi and Lamia spotted Yolda, one of En's wet nurses, and tried to catch her when she spotted them and ran. When they caught up with her, they soon discovered that Prince En was staying in the room next door to the one they were using. Furuichi and Lamia get trapped by Yolda's powerful Dimensional Transfer magic. Hilda suddenly appears through the use of Alaindelon's new power using the demon communication device that Lamia was carrying. She defeated the three wet nurses in a blink of an eye. She also commented on how disgusted she was with the three. Hecadoth, Graphel, and Naga appeared. Hecadoth tackles Yolda. Hilda aims her sword at his neck and told him she would be who he fights. Hecadoth, insulted, began to mock Hilda, who attacked him with her demon powers in retaliation, sending him up twenty floors above. She was about to fight until Oga took the reins and told her she could tag out and let him fight all three of them. She agreed.

Akumano Academy Arc
Hilda has been captured by Behemoth who revealed that Hilda is to become En's new wet nurse, but Hilda refuses.

Behemoth puts Hilda in a cell next to Yolda who is being used to get the rest of the Pillars to Earth from the Demon World. Hilda learns that Yolda is helping Behemoth because he promised her that once all the members of the 34th Pillars are brought to Earth he will let her be with En. When Hilda tries to convince Yolda to stop before she dies from exhaustion, she refuses. Hilda manages to switch places with Yolda on the last day of the transfer and learns that the transfer was already over and the two guards were planning on assaulting her sister. Once Hilda learns this, she beats the two guards unconscious to protect Yolda. Hilda manages to beat five Pillars and allows her sister to escape, but Hilda is captured and crucified. Pillar Head Salamander decides to use his Lost Priminece, a fire which burns all of the person's memories. Meanwhile, Oga invades Akumano Academy alone to destroy Behemoth's 34 Pillar Squad Division and save Hilda.

Upon hearing from Salamander that Oga was on his way to Behemoth, Hilda uses up a lot of her remaining energy to scold Oga from the top of the school, asking if he was stupid. She commented on how reckless it was for him to go in there alone, endangering her master again. Oga, angered, answered back that he came to save her and she should just shut her mouth and wait for him. Hilda was shocked and did not speak from that point on.

Oga defeats most of the pillars with the help of Tōjō, the Red Tails, Izabella, and Satura. When Oga and Tōjō get to the roof, they pretend to be under the influence of Salamander's Flash, dance and quickly dispose of Salamander. When Beel starts making noise at Oga to save Hilda, Jabberwock asks Oga if she is clouding his judgment, and shoots demonic energy at her, intending to kill her. The demonic cloud destroys the cross Hilda was bound to, but Oga appears holding Hilda in his arms unscathed. Hilda, barely conscious, raises her hand to touch Beel's face, saying she is glad that he is all right, and blacks out. Jabberwock laughs at her and calls her stupid, which angers Oga. Oga and Tōjō then start fighting Jabberwock.

Memory Loss Arc
The next day, after Akumano Academy was burned to the ground, Hilda wakes up and finds she does not have a recollection of who she is. When she explains what happened to Oga's parents, they try to refresh her memory by explaining to her who she was (the information was false). She currently believes that she is Oga's wife, as well as Beel's mother. She is brighter and far more kind without the heavy burden to serve and protect her master, not remembering she had spent so many years killing her emotions. After all the pandemonium, Oga, tired from all the events that have happened, falls asleep. He wakes up to find Hilda sleeping next to him. He runs away, afraid of this new behavior, while the confused Hilda calls out to him.

Determined to find a way for Hilda to regain her memories back because of her unusual behavior that even he can't take, they go to school. They met different people: the Red Tails, Himekawa, Kanzaki, the Six Holy Knights, and others. They all failed to give her any recollection of her memories. On the roof, Hilda questions Oga if she really needs to get her memories back. She becomes scared that if she regains her memories, she will lose the feelings of happiness from that moment. Hilda infers she'd rather not get her memories back since she thinks she's happier that way. Oga holds her shoulders and told her with a grim face that the Hilda they know was a violent and merciless woman, taking off all hope for her to regain her memories back.

They meet Kunieda soon after, and out of women's intuition, Hilda introduces herself as Tatsumi's wife, which shocks the life out of Kunieda. A small, violent conversation develops between the two women, with amnesiac Hilda thinking that Kunieda was her husband's wife. Kunieda disapproves of Hilda's conclusion and asked if she based that idea off hers. Hilda then asks if she doesn't harbor any feelings for Oga, which Kunieda answered with a stutter. Kunieda then ran away, red.

At lunch, Hilda and Oga go back to the rooftop. Hilda made a cutesy lunch box for Oga. Furuichi, filled with jealousy, tries to get the lunch box. Oga, after pushing him aside, tells him that the food was the only thing that got better when she lost her memories, then gulped it down. Furuichi then turns to Hilda to ask for a lunch box as well, only to see her face to face with Yolda. Yolda shows a CD in her hand that she claims is a way for Hilda to get her memories back. Hilda refuses the offer. Yolda shouts that she should get her act together, which Oga agreed on. Hilda's eyes teared up, and she asks the gang if she was really that unwanted. Hilda then runs away.

When Yolda, Oga, and Furuichi watched the tape, they see some of the Pillars by the river trying to catch crayfish. They soon discovered that the only way for her to get her memories back, as described by Salamander, is to get a kiss from her "Prince Charming". Oga threw the keyboard at the screen and destroyed the computer, as he assumes that he is her "Prince Charming". He asks Furuichi and Yolda, with the evilest face, if they heard something, and feigned ignorance. Soon, all of the students knew about the kiss that was said to happen, making Oga hide for his pride. Lamia appears out of nowhere and gives Oga a potion that Dr. Forcas made specifically to restore Hilda's memories. Oga then looks for Hilda with Beel as a tracker.

They find Hilda by the river, having been bullied by the Pillar's soldiers. Oga then defeats them mercilessly. Hilda thanks him and grabs his arm to look at the scars. She then sees the potion, which he puts into his pocket. Realizing that it was a cure for her to get her memories back, she promises to take it. She smiles and told him that even if the "new" Hilda might disappear, the "old" Hilda from before was probably happier. Then the potion flew into the river, shocking everyone except Oga and Beel. Faking disappointment, Oga tells Beel that Hilda won't return to normal anymore. He told her that despite her personality change, she was still Beel's mother. Oga handed Beel to her and she gave him a light kiss. Oga commented that maybe it was better that way since the food she makes is better. Hilda then asks him if the food she made back then was really that bad and Oga answered honestly, telling her that it was like "attempted murder", only to realize that Hilda has regained her memories. It turns out that Baby Beel was the "Prince Charming" that Salamander told them about. She answers with an evil smile that next time it won't be attempted murder, and beats the shit out of Oga.

Mobichi Arc
Hilda and Alaindelon assist Oga's Mother in drying clothes outside while Oga and Baby Beel are at school.

Lamia approaches Hilda, who remarks that she is being noisy. Lamia then asks her about the tissues that were sent from the Great Demon Lord, which Hilda states are in Furuichi's possession, noting how he has been complaining about them since. Her attention is immediately sparked after Lamia states that Doctor Furcas strictly advised against the usage of the tissues. The two have a discussion inside the house where Hilda learns that the tissues can be used to summon a powerful Demon from Behemoth's 34 Pillar Division. Despite the dangers, she laughs it off, stating that even Furuichi would not be so dumb as to use the exact method for summoning Demons with the tissues.

However, the two end up going to Saint Ishiyama Academy to see whether everything is actually fine. They find the homeroom for the Ishiyama delinquents and discover that Furuichi has already undergone the summoning ritual. Upon this revelation, Hilda remarks with disappointment that the situation ended up like she had suspected. Oga asks Hilda why they are present. Before she can answer, Yuka and Chiaki begin fawning over Lamia, prompting her to say that they will need to change locations.

The group ends up going to the rooftop of a nearby building, where Hilda and Lamia explain about the tissues. Afterward, they see Furuichi in the hallways and Hilda tells Oga that he should observe for himself if he wants to know more. Hilda and the others then watch as Furuichi gets himself into a fight with Kanzaki and Himekawa, using the powers of Hecadoth and then Agiel. She later remarks that his cockiness during the fight is a sign of Furuichi's stupidity, mockingly referring to him as "Creepichi". She glances at Oga briefly when he says that he will be the one to defeat Furuichi before Hilda focuses back on Furuichi. Upon seeing him summon Jabberwock, she becomes stunned, then speechless after seeing Furuichi win against Tōjō. Later, while Lamia explains about the toxins in the tissues, Hilda mentions that they are a side effect of its use. After learning that the toxins can be fatal, Hilda becomes surprised. Hilda's emotions turn to anger after Oga states that he will be using the bathroom -- something she interprets is another way of saying that he will fight Furuichi. She scolds him for his apparent recklessness and is subsequently silenced after he repeats his statement.

In the evening, Hilda and Lamia go to the river where they watch Oga and Furuichi confront one another. Hilda intently observes the two from afar. After watching them derail the main situation, she becomes annoyed and mentally asks that they just start fighting. Eventually they do, and after some time, Furuichi summons Behemoth to the battlefield. Hilda immediately becomes stunned to see the powerful Demon, becoming further shocked by the subsequent intensity of the fight. As the fight comes to a conclusion, Hilda and Lamia run toward the river and see Oga emerge from the river waters with an unconscious Furuichi on his back. Hilda then watches as he then collapses beside his close friend.

Hilda later takes Baby Beel and holds him in her arms while the two teenagers undergo treatment. With Behemoth still present, she asks why he is still there and remarks that he would have been able to easily kill Oga while lending Furuichi his powers. Hilda listens to the old man as he talks, then watches as he disappears into the sunset. Hilda eventually sets Baby Beel back beside Oga, who eventually wakes up and starts walking away, ignoring Hilda.

Hilda walks home alongside Oga, Furuichi, Lamia, and Baby Beel. When Furuichi hands back his tissues, she insults him for wasting a gift from the Great Demon Lord. Afterwards, she then takes them back with the intention of burning them, adding that Furuichi should not be using them again and thus will not have to rely on them. The group then continue on their way home.

However, Hilda later returns the tissues to Furuichi, telling him that she only persuaded him to give them up so that he would. She explains that she wants him to protect her master whenever she is unable to help him herself, knowing that she will not always be beside him.

Saint Saint X'mas Arc
Christmas is near; however, Hilda has no idea what Christmas is. Misaki explains that it is when Santa Claus comes and gives gifts to good children. Hilda questions such generosity, and asks if it’s Satan. After explaining more clearly, and being told that she and Oga were Beel’s Santa Claus, Hilda gets excited and tells Oga that she wrote a list of what Beel would like. Oga says that if it’s money, he doesn’t have any. Hilda says that she knows how much he lacks financially and hands him the list – Oga’s soul, fifteen loyal servants, and Demon World Monster Gorgonzola. After much thought, Hilda concludes that Gorgonzola is a definite winner. Oga, however, states that it’s a pain, and that a mechanical pencil will suffice. This angers Hilda and they erupt into an argument. Hilda reverts her attention to Baby Beel, as it is his milk time. She orders Oga to get the milk, in which Oga throws it at her, asking if it's "what a demon attendant should say”. Baby Beel attempts to catch the bottle, resulting in Hilda falling down with him. Their lips touch, and Hilda’s ‘amnesiac’ personality returns. Hilda asks if Oga remembers her, which he replies with a shocked face. Oga then tries to get Beel to kiss Hilda again, but after thinking about the current situation, he asks for the current Hilda to stay so he wouldn’t have to get Beel anything demon-related.

Hilda blushes, which causes Oga to experience a bit of guilt. The next day, Hilda sees an event notice – “Couple Limited: Saint-Sent Christmas”. The two enter together for Beel’s sake (and because it’s free), much to Aoi’s dismay, as Aoi was planning to invite Oga to do it with her.

The first event, which was the “Three-legged deathmatch”, results in Oga using Beel’s power in order to win. However, the Izuma-Kunieda pair came first, and Tōjō-Shizuka second, while Oga and Hilda managed to get third place. The next round was organized in tournament form. Oga and Hilda’s challenge was to fight against Oga’s teachers, Zenjūrō Saotome and Suiten Ikaruga. Ikagura introduces herself as Saotome’s wife – thus the announcer concludes this is indeed the fight between Ishiyama’s strongest married couples. The two babies --Baby Beel and Black Beel -- start fighting. Black Beel punches Beel, causing him to fall into Hilda, touching her lips. Saotome states he is happy that Hilda had lost her memories, as he knows Hilda hates him for groping her chest. Oga remarks that Hilda would have destroyed the gymnasium and that Saotome was going to get killed. Hilda interrupts the conversation, asking if she should destroy the gymnasium. However, the two ‘shitheads’ would get caught in it as well. Both Oga and Saotome show faces of shock as Hilda returns back to normal.

However, the announcer reveals that it wasn't just a fight – the “Heart-pounding Glued-together Balloon Breaking Game” was the challenge. Partners must put the balloon in between them so it will not fall. They then have to wear sandpaper gloves – meaning if they touch the balloon, it will pop. The pair that pops the other pair’s balloon wins. Hilda frowns, asking Oga,“What is with this nonsense?”. After explaining, Hilda agrees to take the challenge – winning it with whatever it takes.

The fight starts with the two pairs jumping high above – the two men start fighting in the same way the two babies did, while the two women start a verbal war. Saotome laughs, asking if Oga had trained. He punches Oga, resulting in the Oga-Hilda pair to fall down. Hilda uses her demon powers to break the fall. Ikagura uses ‘foxfire’, which Hilda blocks and manages to dodge the explosions. In the end, the Oga-Hilda pair managed to win by using teamwork – but mainly Baby Beel as bait.

Oga and Hilda manage to get to the semi-finals, in which they are to challenge the Tōjō-Nanami pair in a game of "Twister Karuta". For this challenge, the women face off - trying to get the card that the speaker says before the other person. Written on the card is an attack, where the men would use to get the other off the mat. Hilda, not knowing how to play, gets the wrong cards - allowing Shizuka to easily win for Toujou to attack Oga. Hilda does manage to get a card, but alas the card had a useless move. Finally getting the game, Hilda tries to get another card; sadly, she gets the wrong card.

Shizuka grabs the right card with the attack 'chop' written. Toujou smirks and proceeds to chop Oga, however to their surprise, Oga had ripped the map. The challenge resulted in Toujou and Shizuka's loss, as Tōjō's feet have stepped out of the map.

The last challenge is the 'Head on Battle', where the objective is to steal the other pair's star. Since Izuma lost the motivation to continue (because Shizuka lost), Aoi resulted in reluctantly accepting Aiba's help. Aiba declares that he will win and take Aoi, as after the last battle between the two he had trained very hard. The fight starts, but Hilda gets distracted by the sense of Demonic power from Aiba and warns Oga. Aoi takes advantage of this and slams Hilda down to the ground. Aiba takes the star and it looks like a victory for the Aoi-Aiba pair, but Baby Beel had already taken Aoi-Aiba's star. Thus, a draw was declared. The fight continues again, with Aoi looking very confident. Hilda asks if Aoi thinks she has won already since there is a confident air about her. Aoi smirks, replying that she has a 'woman's attitude'.

Both pairs move at the same time, with Aoi thinking that she has found Hilda's weakness and blind spot, and proceeds to attack her left eye. Hilda however, catches Aoi's hand and smirks. She explains that her left eye is not her blind spot; rather, she sees too well with it. Hilda tells Aoi that her eye can see the tiniest of objects and it displays things ten times as slower but because the vision in both eyes is different, she keeps her left eye covered. Brushing her fringe away from her left eye, revealing a solid color, she tells Aoi that for the sake of her Master, she will beat her with all her strength. Hilda attacks Aoi, reading all of her moves. Aoi gets pushed back, much to the surprise of Oga and Aiba. Oga becomes serious then, stating that the only one who was underestimating someone was Aiba himself. Oga proceeds to attack, finishing Aiba with a "Merry Crunchmas". Oga and Hilda collect the stars and are announced as a charmless best couple.

Returning home, the family waits in front of the Christmas tree for Santa. Hilda asks what Beel would like for Christmas - which she claims is the Gorgonzola. Oga retorts, saying that Santa would never bring anything that big in his bag and that the only thing Santa would have is mechanical pencils. The two break off in yet another argument; however, Beel calms them down, explaining (somehow) that the star that Oga and Hilda had worked together to get was the best Christmas present ever.

Return to Ishiyama High School Arc
While Hilda is reading a book and having tea, she is inquired about Baby Beel's age from Oga. She initially tells him that he does not have an "age" since he is a Demon Lord from birth; however, when the question is brought more clearly to her, she tells Oga that Baby Beel is two years and nine months old. When Oga then asks about her being sixteen years old, this causes Hilda to blush, though she simply tells him that it is an unimportant matter.

Sometime later, Hilda and Alaindelon both stand atop the Kunieda residence as they oversee several Ishiyama students having a type of meeting. Alaindelon asks Hilda whether there is really a Contractor within Ishiyama High School whose Demon opposes the Great Demon Lord's kingdom. Hilda does not answer him. Some point after, she informs at least Furuichi about how there is possible of a Demon Contractor attending the high school.

Hilda later heads to Ishiyama where she searches for the Demon Contractor. However, she finds that he has been shrouding his presence, both annoying and impressing her.

She, along with Alaindelon, eventually find Oga fighting a male delinquent named Yōhei Nasu. Interested, they sneak into the classroom where their fight is taking place. She becomes aware of a King's Crest that has recently bestowed itself upon Kanzaki's back. Hilda then reveals her presence as she explains about the King's Crest to the confused teenagers.

Afterward, she remains silent while watching the events proceed. However, she becomes increasingly astonished as the fight between Oga and Nasu progresses, becoming particularly surprised when she discovers that the latter is a Spell Master, then worried when she recognizes an ability that he later uses. Hilda does express slight satisfaction and genuine surprise when she sees how well Oga is handling the situation.

When the fight ends, Hilda and Alaindelon silently leave the classroom to the top of a nearby rooftop, where they confront a young individual, who evidently knows the former enough where he refers to her by her real name. Even so, this fails to waver Hilda's composure. She instead tells the young man that he will have to pay for harming her master as she slowly draws out the sword in her parasol. To her surprise, he reveals a Teleportation Jewel on his tongue, prompting Hilda to slash at him with the sword. Unfortunately, he disappears before she can touch him.

Hilda and Alaindelon decide to make a quick visit back to the classroom from before. After Hilda inquires about the doppelgängers, she informs the teenagers that she unsuccessfully went after a young individual. From the experience, she concludes that the person is responsible for Nasu's immense power and speculates that there is another party involved. Hilda then prepares to leave for the Demon World before she tells Oga to be careful, adding that the next Spell Master has already targeted him.

After a certain number of days, Hilda contacts her master from the Demon World through a video call set up in Oga's television set. Once connected, she briefly explains why she is not physically present before moving on to snide remark on Aoi's King's Crest. Hilda then proceeds to explain about the King's Crest again, adding that without it, Kanzaki and Aoi would have little chance against the other "Killer Six Elements". She concludes her message, saying that they should, at the very least, recruit Himekawa into their ranks.

Hilda eventually returns to the Human World on her personal Ak-Baba. She announces her arrival to those present and tells her master that she has finally returned home, fresh with new information concerning the Solomon Company.

Equipment

 * Parasol Sword: Her main weapon is a thin sword she keeps in her parasol, again fitting her Victorian-era theme. Hilda uses the sword as a medium to channel a great deal of her demonic power in a single attack.

Powers & Abilities
Expert Hand-to-Hand Combatant: As a fighter, she is quite skilled. Her skills gained her the nickname "Oga's Bride" at Ishiyama, as she dispatches her enemies in a similar manner to Oga (shoving her opponents' heads into walls). Even without using her demonic powers, she is shown to be strong and skillful. Saotome once commented that for a non-contracted wet nurse, Hilda is quite skillful and does very well in fighting. When fighting Isabella, Satura, and Yolda in Himekawa's building, it is shown that Hilda is far stronger than what she has shown before. She effortlessly took down En's three wet nurses in hand-to-hand combat in a blink of an eye, as commented by Furuichi.

Expert Swordswoman: Hilda is identified as a skilled swordswoman in that she always carries around her sword hidden in a parasol. She demonstrated the ability to cut through stone with her sword, seen during her first meeting with Oga and Furuichi. However, she rarely draws the sword and especially refuses to do so against weak opponents. She was able to defeat Aoi Kunieda, one of Ishiyama's Tōhōshinki, with little effort. She uses her swordsmanship abilities with implements other than the blade, such as fighting with the parasol/umbrella without drawing the blade or using random sticks or guardrail columns. Recently, Hilda was able to easily defeat three well-known human martial artists using just her sword while still in its parasol form.

Great Demonic Power: As she is still a non-contracted demon, it is conceivable that Hilda's potential full strength has not been shown. Despite this, it's been shown that in the Human World she is a force to be reckoned with, as she was able to easily defeat all three of En's maids in a flash, as well as Zenjūrō Saotome while Oga, Tōjō, and Izuma were easily defeated by the teacher in one attack each (though she was unable to land a hit on him). Later she showed her great power by pummeling Hecadoth (a pillar general) when unhindered, and easily defeated numerous soldiers of the 34th Pillar Division in order for Yolda to escape before being captured. Enhanced Strength: Hilda's strength has been noted by quite high. When she first fought against Oga, her attack shattered Furuichi's bedroom and is seen comparable enough to Oga that the delinquents of Ishiyama called her Oga's bride. She is powerful enough to shove Hecadoth up through twenty floors in Himekawa's building with ease.
 * Aura Manipulation: Hilda is able to manipulate her demonic aura as a mass of black filaments for numerous purposes. When united together those filaments seem to have a great destructive power, but Hilda seems to be able to use small filament-made whips to grab things like she does when she takes the guardrail staffs to fight with Kunieda, or when she caught Oga while falling down from Sodom.
 * Energy Punch: Hilda coats her arm in a mass of demonic energy to enhance her punches that can instantly take out a soldier of 34th Pillar Division.

Enhanced Endurance: Hilda is durable enough to try and plead for Baby Beel to run for his life along with Oga, despite having been stabbed through the abdomen by Hecadoth's demonic energy diffusing spear. She was able to fight against a number of soldiers of 34th Pillar Division by herself for a considerable amount of time before being captured.

Enhanced Speed: Hilda is very fast, as she was able to take down En's maids in an instant before anyone of them managed to register her movements. When unhindered, she was able to pummel around Hecadoth before he could react. During her fight with Saotome, Hilda was able to make attacks fast enough that she was able to pressure the teacher (though he had no real intent on fighting her).

Conveyance
Despite the fact that she is naturally just as fast as strong she is as a demon, Hilda rides a giant bird-like being named Ak-Baba, though she has not been shown riding it lately.

Tatsumi Oga
Hilda's relationship with Oga is one of the most complex relationships of the series. Hilda often looks down on him and never hesitates to mock him. In turn, he finds her cold and manipulative personality annoying. However, it is shown on rare occasions that they do care about each other, such as when Hilda thanks him for helping her get Beel back from Toujou and when Oga became enraged at Hecatos for harming her. It should be noted that the two work extremely well together in a fight. They are also known as "The Most Evil Couple" and "The Strongest Husband and Wife". Hilda is already considered as Oga's apparent bride/wife by the whole Ishiyama school and his family, gaining her nicknames such as "Oga's bride", "Wife", or "Wifey". Both of them don't bother to correct other people's opinions, considering it a waste of effort to explain.

As the chapters pass by, Hilda's and Oga's relationship has grown by leaps and bounds naturally, even Oga's family has accepted her presence as a family member, especially his sister Misaki. Although they still constantly bicker, Hilda has gained Oga's utmost respect and vice versa. A pinnacle point in their relationship occurs when Oga saves her from being kidnapped by Jabberwock. Realizing that Oga's tactics wouldn't stop Jabberwock, she pulls Oga close and tells him that she is leaving Beel in his care alone, giving him a rare sincere smile. She then allows herself to be taken by Jabberwock's dragon in order to save Oga and Beel. Her parting words were, "You're...the only father he has in this world", implying she has finally accepted Oga as Beel's parent.

Oga goes as far as to breaking into Akumano Academy alone in order to rescue her. When Oga arrived at Akumano, he received a very loud scolding from Hilda. She says that he is endangering Beel again and that he is being very reckless and stupid. But Oga shouts back just as loudly that he came all that way just to save her, and that she should shut her mouth and wait for him. Surprised, Hilda's eyes widen and she stays silent. As the battle between Behemoth and Oga unfolds, Oga makes Hilda's rescue his top priority. Being impatient, Behemoth surprises them with a beam of demon power, aiming it at the crucified and unconscious Hilda. Oga moves quickly to get Hilda before getting hit by the blast. The barely awake Hilda caresses Beel's cheeks and tells him how glad she is that her Master is safe before completely losing consciousness. Behemoth laughs and comments on how stupid she was. Oga becomes filled with anger and tells him not to laugh at her. He attacks Behemoth due to him mocking her loyalty.

By the time the Akumano High arc ended, his care for her has grown even more, admitting that he couldn't bring himself to tell Hilda the truth about their situation, simply because he saw how happy she was when she didn't have her memories. He seemed to be shy when people said Hilda was his wife. When they finally find the way to cure Hilda, which is a kiss from her "Prince Charming", he smashes the computer monitor with the keyboard, trying hard to pretend that the event never happened.

It is unknown whether or not he was thinking the "Prince Charming" was him, given that Hilda had developed romantic feelings for him during her memory loss. She commonly calls Oga a "damn fool", though recently the term seems to have become less of an insult, and more of an affectionate gesture. After regaining her memories, she claims not to remember anything from the time of her memory loss (though it's possible she is lying). After returning to normal, she still occasionally calls Oga by his first name, "Tatsumi", and is the only one (excluding his family) who Oga allows to call him that. After saving her from Behemoth, the two have grown much closer and more comfortable around each other. They can often be seen spending their free time with each other, though Hilda insists that it's only for spending time with Beel.

Aoi Kunieda
Aoi has seen Hilda as a rival ever since the fight between the two of them. Aoi is seen being jealous of Hilda for being Oga's "wife" when it is just a misunderstanding of hers like every other student in the school. They start to get along with each other after the St. Ishiyama Arc. However, it almost immediately degenerates back into a fiery rivalry when Hilda becomes jealous of Beel's affection toward Aoi. Despite still being jealous towards each other, Hilda still respects her and sees her as a worthy opponent.

Lamia
Lamia has a great amount of respect for Hilda. Commenting on how beautiful Hilda is and called her a breast idol because of the size her breasts. She also refers to Hilda as "Hilda-nee-san" or "Hilda-sama". When Hilda asks her to find Lord En's whereabouts, Lamia tries her best to look for him, along with Furuichi and the other Ishiyama delinquents.

Misaki Oga
Even though Misaki is just one of the sideline characters, Hilda's closeness to Misaki is very clear. In the beginning, Oga's family easily welcomed Hilda and Beel into their family, and Misaki was shocked at how big her breasts were. This might have been because she too was endowed with large breasts. As time passes by, Misaki grows fonder of Hilda's presence. Hilda is very obedient to Misaki, making her a perfect sister-in-law in Misaki's eyes. When Hilda disappears when Beel gets sick, Misaki kicks Oga out of the house and does not let him back in until he finds her. She also comments on how Hilda and Oga berate each other as a normal couple would, calling it their 'love quarrel'.

Yolda
Despite being sisters, Yolda has disliked Hilda for a very long time and hates being inferior to her. What she hates the most, however, is that their appearances are remarkably similar, borderline identical, something Hilda reluctantly agrees with. Hilda still seems to care about Yolda, enough so to save her from prison before she overworks herself to death, claiming she doesn't need a reason to save her sister. It seems that the relationship between them is not publicly known by many people, only known by Oga, Furuchi, Lamia, Izabella, and Satura. Even Lamia is not aware of this until Izabella tells her, stating that Hilda never mentioned it.

Iris
Hilda served Iris before Beel was born. She is the only person that treated Hilda like a family. Because of this, Hilda thinks of her as an older sister.

Quotes

 * "Mas...ter... Please... get a... way... " (Referring to Beel, when stabbed by Hecados)
 * "The one who can barely think straight because of this anger, because her master was put in danger...is me." (Referring to En's three wet nurses)
 * "You make me sick, thinking that you're wet maids like me." (Referring to En's three wet nurses)
 * "Somewhere over the rainbow... When you wish upon a star..." (Calming herself down)
 * "You damn fool." (To Oga, multiple times)
 * "You're...the only father he has in this world." (To Oga)
 * "Look at me...thinking of his words at a time like this. My life is supposed to be my Master's alone." (When she catches herself thinking about Oga when imprisoned)
 * "Why?.. As if I need a reason to help my sister." (Referring to Yolda)
 * "I'm...his wife." (After finding out Oga is her "husband")
 * "Th-then.... What is it about me that you don't like?"  (To Oga)
 * "I will not stop! You look silly with snot running down your face!" (To Oga, referring to his cold)
 * "It's nice to meet you. I'm Tatsumi's wife, Hilda" (To Aoi)
 * "No. I'm saying this man is my husband" (To Aoi)
 * "Tatsumi, who is this... whore?" (To Oga, referring to Aoi)
 * "Tatsumi...." (To Oga)
 * "You have me, your wife, right here. But you have the nerve to keep another woman on the side?" (To Oga)
 * "Then, does that mean that you don't have any feelings for Tatsumi?" (To Aoi, referring to Oga)
 * "Am I... Really that unwanted?" (To Oga, referring to her memory loss state)
 * "Do you think you've actually grown a pair, bitch? Fine. Next time it won't be attempted murder!" (To Oga, after he insulted her cooking)
 * "My only wish is for my young master to be the best demon lord there is. And...you Tatsumi, are the man who can do that" (To Oga)
 * "Because this is your field of expertise. Since you're a pedophile, you know how to speak to little girls like this." (To Furuichi, about Futaba)
 * "The four martial kings...? Don't make me laugh. Kunieda, by herself, is still a more formidable opponent. (To the four martial kings after beating them)

Trivia

 * In episode 7 of the Beelzebub anime, Hilda is shown to be a fan of soap operas.
 * It was hinted that she is hundreds of years old despite her appearance since Yolda says that the last time they met was hundreds of years ago. However, in Chapter 187, it is revealed Hilda is 16 years old. Yolda was probably just exaggerating the fact that they haven't seen each other in many years.
 * Oga's schoolmates refer to her as "Oga's bride", "Oga's wife", "Wifey", and "Blonde Bombshell".
 * She often mistakes kanji for brutal and weird words.
 * A wet nurse's main job is to breastfeed their master's infant child if the mother is unable to, though Hilda has never been shown breastfeeding Beelzebub.
 * In episode 48, an animation error occurred with Hilda's face. The front of her chin went missing.
 * It was revealed in chapter 166 that Hilda's necklace was a gift from Beel's mother, Iris.
 * The name Hildegarde is derived from the Old High German words hild (war or battle) and gard (protection), and means "protecting battle-maid".
 * Amnesiac Hilda didn't know that demons exist, or the fact that she is a demon herself.
 * Chapter 86 of the manga 'Sket Dance' makes a reference to the character. When Himeko was dressed as a maid, her friend commented that she looked like Hilda.
 * Hilda's voluptuous breasts have caught the attention of some girls, including Oga's older sister Misaki, as well as two schoolgirls with Himekawa.