Katakura Kippei, a notorious high school flirt, suddenly finds himself thrust into the role of a full-time caregiver for his 5-year-old cousin, Yuzuyu. Left by his aunt Miyako, who mysteriously vanished, Yuzuyu grapples with the pain of her mother's absence while Kippei struggles with his newfound responsibilities and ignorance in childcare. Together, they embark on a turbulent journey of growth and understanding. Adapted from Maki Youko's manga.