Kishimoto Kasumi, a 15‑year‑old, was set to move into her aunt’s house in April so she could attend high school. When she arrived, she found that four new male students already lived there. To make matters worse, that same day while she was taking a bath, Takasugi Yusaku, one of the boys, unexpectedly entered the bathroom and saw her naked. Thus began Kasumi’s tumultuous high‑school days.