Ryuuya Hyuuga
A professor at Saotome Academy. He works mainly with the students from class S.
In episode 3, he has a confrontation with Ichinose Tokiya about his grade. Tokiya feels that he did everything perfectly and did not deserve a low grade. However, Prof. Hyouga replies that while doing everything perfectly, he does not have any heart in his music, and that is his downfall. He even goes as far as saying his twin brother has more heart than he does, making it a deeper blow. He also went further to say that if he continued to have no heart he would not be in S class for much longer.
It is also revealed in the games that he had a close friend as his partner who was a song composer; however, they died rather young. Ever since his death, Hyuga refuses to sing (at least in the Sweet Serenade route.