Haiji Kikuno is a pansexual transfer student at Sakashitamon Academy. He is popular with the girls of his class except Sakurako. He fell in love with Hachibe because of his pureness of heart, much to Hachibe’s displeasure.
Through an accident, Hachibe learns that Kikuno has his ideal butt, causing Hachibe to have mental anguish because his part fetish is not strong enough to overcome the gender issue, but it has died down enough that they seem to be good friends in later chapters as well a supporting anyone else who has feelings for Hachibe.
Though that doesn't stop him from trying to get Hachibe, even though he is always beaten up for trying. It is later revealed he has his "love all" personality due to the fact that his mother and stepfather never loved him.