Mamori Wataya has consistently remained unnoticed in her school due to her tall and unremarkable appearance. She has resigned herself to being a supporting character. However, when she befriends Soushi Fuji, a brusque classmate who uses a cane and takes revenge against those who underestimate him, she discovers a new pathway. Can Fuji help her embrace her darker side and transform into a villain like him? When Fuji requests that Wataya drain the school pool for him, she experiences her first taste of the exhilaration that comes from breaking rules. Inspired by the villains in anime and manga that she admires, she is now ready to try something a little mischievous. Although she may not be prepared for serious criminal activities, she knows she wants to start doing something wrong.