Quartet Night's Composer (Uta no Prince-sama x Reader)

[[COMPLETED]] You, (Y/n) (L/n), are a composer for one of the popular idol group, Quartet Night. You've known the group since day 1 of the Master Course for the both of you. One day, a new idol group entered, they were called STARISH. The five of you were then assigned to be the senpai (senior) of STARISH. However...