Hiding in the school toilet, Daichi Shinagawa curses upon the fact that his idle high school life is suddenly interrupted by an annoying presence—the class representative Hana Adachi. Unfortunately for the delinquent, the eccentric Adachi enters the male washroom without hesitation and discovers his hiding spot in a flash. Going on a field trip with his classmates is the least of Shinagawa's concerns, but that is the very thing that Adachi would not give up on. By hook or crook, she insists that everyone in the class attend the trip, including the reluctant Shinagawa. To make matters worse, despite his constant rejection Adachi would keep following Shinagawa even after school has ended.

However, after an encounter with a pair of purse snatchers, Shinagawa soon learns that Adachi has an unexpected side to her, and is soon thrust into chaotic school life filled with her inescapable antics.