Hayato Yamamura, a 16-year-old boy, is trying to cope with the divorce of his parents. Living with his father, Taro, has been challenging, but Hayato has grown accustomed to their quiet life together.
However, their world is turned upside down when Taro his Dad announces his remarriage to Rina, a woman with three daughters Natsumi, Erika and Naomi. Hayato must now adapt to a new family dynamic, sharing his father's attention and living space with his step-sisters. As Hayato navigates this unfamiliar challenges.