On his first day at the academy before the term begins, staff member Joutarou uncovers a concealed side to the conduct of students Mitsuki and Minami. He also hears of the striking grade improvements shown by Mahiru, younger sister of Classics instructor Hinako, and notices signs of her discreet involvement. Resolved to correct these rule-breaking patterns, Joutarou prepares to guide the students toward proper behavior.