Toudou Miyuki and Sanada Eiji balance their roles as fellow teachers with a private vow to save their intimacy for marriage. Their commitment faces sudden strain when Eiji’s stepbrother Takuya arrives at the school and directs his focus toward Miyuki, resulting in a shattering violation of her trust. The encounter leaves her shaken and uncertain, while Takuya’s attention begins to extend toward the other female instructors on staff.