They first met when Otoya defended Haruka 's right to enter the entrance exam with Ren. Later on they find out they are in the same class.Haruka is Otoya's partner in their first assignment in the school.Since Haruka didn't know how to read music, he encouraged her to do her best about it. Otoya couldn't come up with the lyrics even after consulting the other guys for tips. It is not until he hears Haruka humming a theme that he finally gets inspiration. They created the song "Brand New Melody", and they both passed with high scores. In episode 8, Otoya confesses that he loves Haruka...'s music, and is going to request her as his partner for the graduation audition. In the end, he is in the group ST☆RISH with the other five people who also requested Haruka to be their partner.
In Season 4 Episode 1, he holds Haruka in a romantic pose before confessing that he loves her...music.
Tokiya is Otoya's roommate. He's the complete opposite of Otoya and seems to find his roommate a bit bothersome at times. Tokiya is a calm perfectionist, whereas Otoya is very childish. Tokiya gives him pointers about how to come up with lyrics (reluctantly), even though Otoya has a hard time understanding him. However, over time, their relationship begins to loosen up.
He is Is one of his colleagues and a part of STARISH.
The two get along fairly well, as they have never been depicted fighting.
Otoya has proven that he trusts Natsuki, and often turns to him for advice. He once requested his help in baking so he could cheer Haruka up, but was horrified when he saw how terrible Natsuki was at it. Otoya was then forcefully fed some of what he had made, and promptly fainted as a result. He often helps Syo in holding Natsuki back.
Otoya appears to be good friends with Syo, and is often seen helping him hold back either Natsuki or Cecil depending on the situation.