Hikaru Osari Edit
Hikaru and Tatsuhiro are best friends, having a deep relationship with each other. It is shown that they met even before the auditions for B-Project. It is shown, however, in episode 7, that Tatsuhiro can be quite protective of Hikaru.
Kazuna Masunaga Edit
Tatsuhiro is very fond of him, and the two are band-mates.