Fifteen years ago, his mother died in a plane crash, resulting in him having to be brought in at an orphanage. Also, he has never "met" his father, who is in fact Shining Saotome. His adoptive mother, who is a Christian, also gave him a rosary that he keeps with him.
Haruka's classmate in A Class. He's a friendly and positive person who enjoys singing. He shares a room with Tokiya from Class S. In the anime, he stands up for Haruka when she was barred from taking the entrance exam due to being late. He enters the Academy partly because "singing seemed fun and interesting" but after meeting Haruka & hearing one of her songs, he falls in-love with her caring, hard-working and "never-give-up" personality and starts to pursue becoming an idol seriously. He is somewhat intimidated by Ichinose since the beginning because of his "perfect singing".
They first met when Otoya defended Haruka 's right to enter the entrance exam with . 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,  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.
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.
Cecil is a friend and band-mate of Otoya. The two get along pretty well, Otoya was one of the few that was immediately friendly with Cecil when he first arrived, but he doesn't like his romantic advances towards Nanami, like the rest of STARISH. He indirectly helped Cecil want to become an idol when the two worked on a TV show together. Otoya was also one of the first few to say that Cecil should join STARISH after they all sang together and was thrilled that he joined, he also pleaded with Saotome with the rest of STARISH to allow Cecil to join, which worked after they performed for him. It's later revealed that the two are half-brothers, the two born from the same mother, but different fathers.