Seemingly unsure of what to make of Mafuyu who Ritsuka out of the blue brings him to band practice, Akihiko identifies the positive impact he has on Ritsuka's performance aspects. Akihiko is patient with Mafuyu but tends to give Ritsuka the space to help him.
The drummer in Ritsuka's band, Akihiko works with him well there and at a convenience store and a moving company with him.
Akihiko becomes increasingly aware of how Ritsuka may feel about Mafuyu but pre-emptively breaks the ice assuming that something had happened between them, with what Akihiko and Ritsuka's assumptions about what the problem was being different. Though a hurdle, Akihiko alleviated any tensions Ritsuka may have had by sharing his past experiences.
Akihiko and Haruki become friends after Akihiko was asked to enjoy the band from Haruki. Akihiko often shares knowing glances with Haruki when suggestions like performing together are made. He likes touching his long hair and Akihiko has romantic feelings for Haruki, even though he doesn’t realize it until the end of Summer, before the CAC event.
After Haruki helps with Mafuyu's broken guitar strings, Akihiko tells him he thinks Haruki is always saving things. At that point Akihiko relates it to himself, that he used to be really irritable and thanks Haruki for inviting him into the band. He tells Haruki it is fine to like himself more.
After a fight with his ex-boyfriend Ugetsu, Akihiko begins to live with Haruki. During their cohabitation, Akihiko finally realizes his romantic feelings towards him. After the CAC Event, Akihiko begins to change in order to become a better person for Haruki. In spring, Akihiko attends a violin competition, Haruki and Mafuyu go there without telling him. But overwhelmed by Akihiko’s sophisticate and raw passion, Haruki leaves before the end of the competition, telling Mafuyu that he doesn’t feel well.
Later Akihiko finds Haruki on the riverside and they have a discussion with Haruki asking why he becomes distant from him; he answers that he broke up with Ugetsu and got in touch with his parents to beg them for money. At the same time he left all his jobs, dedicating himself to play the violin. When Haruki continues asking questions Akihiko stops him saying that he changes his way of living to become a good enough man for him. After a silent, embarrassing moment he asks Haruki if he can touch him; Haruki says “yes” and Akihiko hugs him, confessing that he is in love with him and asks for another chance. Haruki accepts becoming his boyfriend.
He was referenced as an unnamed roommate of Akihiko's who is considered family. They are then shown to be very close to sharing the bed and enjoying their time together when Ugetsu is not abroad.
Akihiko met Ugetsu during the summer of his first year in high school, becoming his first friend. Later, they got together. Akihiko, during his third year in high school, using his parents’ divorce as an excuse, went to live at Ugetsu's house.Ugetsu broke up with him after two years together; however Akihiko continued to live with him. Since then their relationship has ups and downs, with both of them having occasional other partners, even though Akihiko can not give up on Ugetsu. Akihiko is supportive of him feeding him some of his breakfast in bed and spending time together. They share musical interests practicing violin together and Ugestsu attends Akihiko's live performance with his band.
When Akihiko finds out Ugetsu with another guy in their bed, they have a final and violent fight, then he leaves Ugetsu‘s house and goes to Haruki‘s.
His father is a violinist and lives in England.
His mother is stated to be resting leisurely at home.