Kōta Kunieda

Appearance
Kota is a infant and is the same size as Beelzebub. He is sometimes shown on the back of his sister. Kota is shown wearing a long-sleeved blue shirt with the number 5 in the center. He also wears blue pants. On the top of his head he wears a bear hat, and on his feet are brown shoes with a white background. Kota shares an appearance a bit similar to Aoi, except that he has black hair and big black eyes, unlike Beelzebub, whose eyes are small.

Personality.
Kouta is shown at first as a normal infant, but shows pleasure by tormenting Beelzebub. Later, Kouta appears to have a rivalry and a close friendship with Beelzebub. Kouta seems to care about his new friendship with Beelzebub like watching hero shows together with him and being together to fight bullies.

Plot

Tōhōshinki Arc
He is first seen while being taken to the park by his older sister, Kunieda Aoi, where many mothers in the park mistakenly believe that Aoi is his mother. While in the park, he has his first encounter with Beelzebub, where he starts fighting him on a park bench when Oga decides that they should have a fight. Kota easily wins the wrestling match by pushing Beelzebub off the park bench, causing Beelzebub to almost cry.

He is then seen with his older sister, Kunieda Aoi, when they go to visit his grandfather. While he was on the trip to see his grandfather, Kunieda Aoi sees him carried on his back.

Saint Ishiyama Academy Arc
He is seen again when Oga goes to Aoi's home which is a shrine so that Oga can train properly for his fight with demons. Throughout the training sessions, Kouta is shown training alongside Beelzebub. Kouta makes Beelzebub continuously cry during the training sessions because he continuously outdoes Beelzebub with a tormenting smile.

Hero Show Arc
Kouta goes to a Hero Show with Beelzebub. It is here where Kouta first meets up with Kanzaki Futaba and is shown to develop his first crush on her. Kouta and Beelzebub enjoy the Hero Show and when the show ends, he and Beelzebub tries to act out some otry characters moves. At the end of the arc, Kouta is being bullied by other children and almost cries before being comforted by Beelzebub. Kouta gains courage and stands up together with Beelzebub against the bullying children before the bullying children are scared away by their elder sister. Kouta and Beelzebub seem to congratulate each other, for believing that it was their efforts that scared away the bullying children.

Saint X'mas Arc
Kōta goes with his older sister Aoi to the shopping district in the city, where they run errands for the family. While in one of the malls, Kōta sees a selection of costume items relating to Gohan-Kun and stares at them intently. Eventually, the two siblings meet with Oga and Hilda at the mall. Hilda eventually buys ice cream for Kōta and Baby Beel, even handing out Kōta's own ice cream cone to him. Afterwards, Oga and Hilda take their leave. While they leave, Kōta feels an enraged aura coming from Aoi and becomes frightened by it.

Return to Ishiyama High School Arc
When Baby Beel is at the Kunieda residence, he and Kōta end up fighting each other, though Oga tries pulling them apart so neither can actually get injured.

Aoi Kunieda
Aoi clearly loves her little brother, as she uses her alter ego in order to distance him from her more well-known identity as the leader of Red Tail, which could potentially make him a target for her enemies. She is usually the one seen taking care of Kōta and is the relative that Kōta responds most favorably toward so far.

Beelzebub IV
Though they are rivals who are constantly trying to outdo each other, they are still friendly at times, as neither appears to have any other friends their age.

Hajime Kanzaki
In an anime filler episode, Kanzaki got the idea of his Double Heel Smash, from watching Kōta roll down a hill.

Koma
In the Anime Kouta and Beel tried helping Koma in getting Aoi to eat his manju (filler).

Futaba Kanzaki
In the manga, Kouta develops a crush on Futaba. In You Can Make 100 Friends, Right? he starts a fight with Beel because Futaba decided to group with Beel.

Trivia

 * In the Beelzebub anime, several filler episodes are often between plot developments. In one such, Kota is shown alone at a daycare playing by himself, because the other boys do not want to play him, When Beel comes along with the cat to play with him, he is happy to see them, both of them eventually beat the other babies in a game of who could stack the highest blocks by causing an explosion.
 * Episode 42 is the first episode to see Kota walking and standing up.
 * Kota seems a bit younger than Baby Beel.