Seikain Jogakkou
Students
Aika Tenkuubashi
Kimito decided to make her a popular girl, thus creating the "Commoner Club". He dubs Aika a "Tsun-pure" not long after meeting her, and greatly enjoys teasing her. This often involves convincing Aika to believe ridiculous notions about commoner-related things, and these instances usually end with her becoming greatly embarrassed and pummeling him. And at first, Kimito though that Aika was quite weird, because she wanted to kiss him out of the blue. But as the story progress, they grow to have a very close bond. They call each other with first names, without any honorfix. (san, chan, kun, etc), which upset Reiko. It is strongly hinted that Aika is closest person to him, and he and Aika often chat in his room, where he enjoys trolling her with jokes about real-life topics that exploit her tendency for pretension as well as her *very real* innocence, so they can freely talk with each other about various topics. It is later revealed that Aika has feelings for Kimito.
In volume 10, Eri asked if Kimito have any girl he is in love with. Kimito replied her that he had feeling for Aika when he met Aika in the past.
Reiko Arisugawa
Reiko and Kimito have a good and friendly relationship. Reiko was interested in Kimito when she first saw him, and she also respects him. And not long after arriving at the academy Kimito walks in on Reiko in the baths and they see each other naked. After this incident, Reiko falls in love with Kimito and often has delusions of marrying him. She, however, doesn't show it too much, but she always tries to get his attention and becomes jealous when the other girl show too much affection to hin. Also, at first, Kimito only called her by her last name, but Reiko got upset about that, so she told him to call her by her first name instead. While spending time in the club, the two become close. When Kimito heard about Reiko's wedding, Kimito wanted to help her to not to get married, because it was against Reiko's will. Kimito succeded, with the help of Karen, Hakua and Aika. Kimito also told Reiko's mother that he is going to take care of her in Seikain Jogakkou. However, her mother thinks it's a proposal, so she agrees, and thinks Kimito is the right one for Reiko. After this, Reiko falls even more in love with him.
Karen Jinryou
At first, Karen disliked Kimito, because she believed that he had defeated her and she makes it clear that her actual desire is to surpass and kill him. He has tried many times to explain the error but is always ignored by the prideful girl.
While spending time in the club, Karen always gets angry when Hakua ignores her because of him. However, after the fortune telling, Kimito and Karen get a hundred points, and after this, she starts harbor feelings for him, but she is not perfectly aware of it. Despite her attitude, Kimito is nice to her, and they once where in Karen's house alone, and Kimito also treasures Karen as very good friend, even though she wasn't very nice to him in the beginning. Also, at one point, she willingly wore pants that reveals her thighs in order to appeal to Kimito's thigh fetish.
Hakua Shiodome
Hakua is very attached to Kimito, and it is hinted that she has feelings for him, but because of her shy and quiet personality, she doesn't show it a lot. However, Kimito is also very kind to Hakua, treating her like a little sister. Hakua usually sits on Kimito's lap when spending time in the club. Furthermore, they are on good terms, calling each other by their first names.
Staff at Seikain Jogakkou
Sayuri Kimachi
Sayuri and Kimito have a quite good relationship, even though they haven't exactly interacted with each other. Sayuri also likes to tease Kimito.
Miyuki Kujou
Miyuki is Kimito's personal maid. Miyuki was the first one that Kimito met when he first came to the school. Being his personal maid, she usually takes orders from him and helps him with easy tasks, like changing clothes. It is revealed in the later volume that Miyuki met Kimito when Kimito swapped place with Miyuki's brother who look exactly like Kimito. After interacting with Kimito during those periods and Kimito saving Miyuki from some bullies in the school, Miyuki fell in love for Kimito deeply.
Due to the fever Kimito caught during the outing with Aika when they first met as preteens, he lost all his memories for the period he swapped places with Miyuki. Miyuki was saddened when Kimito failed to recognize her and he had to return to his original place. Despite these happened, Miyuki still cherish her relationship with Kimito.
Other
Masaomi Arisugawa
Masaomi is Reiko's younger brother. Masaomi dislikes Kimito, because Masaomi is very defensive of Reiko and cares for her deeply, and also because Reiko is in love with Kimito. However, he once helped Kimito, regarding Reiko's marriage.
Eri Hanae
Kimito's childhood friend. Kimito treasures Eri as a very close friend, and they have known each other since they were little. After being abducted to Seikain Jogakkou, they still talk to each other. Kimito also encouraged Eri to become a popular singer since she was teased when they were younger-- and as result; Eri also deeply cares for him and claims that he is her boyfriend.