Misaki Oga

is Tatsumi Oga's older sister. During her teenage years, she was the founder and first leader of the Red Tail.

Appearance
She has shoulder length brown hair with her bangs in the middle and brown eyes. She is usually seen with her orange tank top and blue shorts. She is also well endowed, and the shirts she wears give detail of her breast size.

Personality
While more even-tempered than her younger brother, Misaki is still rather fearsome when angry (to the degree where even Oga will only pick a fight with her up to a certain point). Like her parents, she quickly accepts Hilda and Beelzebub IV as part of the family, and will not hesitate to criticize or physically punish Oga if she sees him slacking off as a parent. She seem to have a good relationship with Hilda and gets mad whenever Oga does something to make her upset. When Hilda introduced herself to Oga's family, she at first was shocked at the beautiful demon's breasts.

History
Misaki attended Ishiyama High School as a teenager where she later founded the all-girl gang: Red Tail.

One day, Misaki asked her younger brother to buy an issue of "Deluxe Beautiful Ladies". Unfortunately, Oga was delayed in bringing her the magazine and Misaki ended up missing a rebroadcast of the television show, Femme Delinquent Cop, putting her in a bad mood. When Oga finally arrived with the magazine, she kicked him and started beating him up for making her wait. Misaki eventually got to check on her magazine and looked through the pages, eventually finding an article featuring the Red Tail. Misaki jumped with joy and started showing the article to Shizuku and Haruka. Later, she overheard the two girls inviting her younger brother and his friend to a party, which Misaki was initially skeptical of.

Misaki and the rest of the Red Tail go the party, revealed to be a battle between a male biker gang from Donbura High School. Misaki led her gang against the opposing group; eventually, they succeeded victory against them. After the fights were over, Misaki went to meet her younger brother's friend and learned that he was Takayuki Furuichi. Nicknaming him "Takachin", Misaki asked that he take care of her younger brother because she thought that he would want a friend.

Sometime during high school, Misaki resigned from her position as leader and passed on the title to Ringo Hōjō.

Misaki later graduated from Ishiyama High School and entered college.

Saint Saint X'mas Arc
In the dining room, Misaki notes that it is almost time for Christmas. She asks whether Hilda knows about the holiday; upon learning that she does not, she explains about how Santa Claus brings presents to good children. Misaki then adds that Santa Claus is different from Satan after Hilda suggests that they are the same person. Explaining once again, she and her mother then reminisce on a past Christmas where Oga got sick from staying up late; however, they then realize that he suffered a near-death experience from the incident. Afterwards, Misaki tells Hilda to pick out a gift for Baby Beel, stating that she and her younger brother are his Santa Claus.

Misaki later gets a call from Furuichi while at college. She is informed about an old rule that she made while leading the Red Tail, which she casually tells him can be broken, as it is a stupid rule anyway. Misaki then laughs at how the Red Tail are love maidens. Moments after, Nene Ōmori takes away Furuichi's cell phone and has a brief conversation with Misaki, ultimately thanking the older girl for being the founder of their all-girl gang.

While going outside on Christmas Day, Misaki notices a package near the front gate and remarks on its foul stench. She tells her younger brother about the mysterious gift.

Return to Ishiyama High School Arc
On a snowy day, Misaki opens the front door to find a "motley crew" waiting to see her younger brother. She happily greets Aoi and Furuichi while she lets them and two others in. She states that she does not recognize the "guy with the lip chain" which incites the delinquent to mock her; for his insolence, Misaki smashes his head in through the front door. Misaki quickly asks Aoi about the Red Tail while she enters her house and is pleased that the gang is doing well. She then takes her guests to Oga's room, noting that he has been busy since the previous night. When the five people enter his bedroom, they see Oga playing a card game with Baby Beel, which bothers Misaki somewhat.

Quotes

 * "TATSUMI-!!" (whenever she's berating Oga, usually followed by a kick or a punch)
 * "Hilda-chan, will you go get that for me?"
 * "I was just thinking of having Hilda go buy some soy sauce..."
 * "Tatsumi! Go and escort this girl back home!" (referring to Aoi)
 * "No matter where you look, you're not going to find a bride (Hilda) like that again!"
 * "You did something stupid and hurt her (Hilda's) feelings, right?! GO AND APOLOGIZE!!"
 * "Until you find and bring her (Hilda) back, you're not getting into this house again!"
 * "You're Beelze's mother. You see that little loser of a brother I have there? I can't believe someone as good as you would be with him, but you're his wife." (to Hilda)
 * "Her boobs are huge?"

Trivia

 * She seems to be fond of ice popsicles, as she's often seen eating one when she appears.
 * Oga once commented on how easily his sister could "boss that demon around".
 * Oga states that the manner how Suiten Ikaruga becomes violent while drunk is similar to how Misaki can be become violent when she is drunk.
 * When Hilda introduced herself, Misaki seemed more focused on the size of Hilda's bust.
 * Misaki is basically a female version of her younger brother due to their similar hair, eye color and bad temperment.