Romance Agreement: Don't Steal A March On Me!

A childish student, Shirou carries a torch for his teacher, Oka. Masami, a good friend of Shirou's, who has cherished him like a brother, is confronted by Ryuuji, another friend of theirs, concerning his true feelings for Shirou. Masami and Ryuuji conclude a gentlemen's agreement, in which neither of them can hit on Shirou. Ryuuji orders Masami to act as a substitute and take care of his sexual desires in Shirou's stead.