One day, the Hanabishi and Hidaka parents were preparing for a long term overseas business trip together. Kouki ended up living together with the four sisters. And one of them is promised to him as a fiance. But who should he choose? First wife material: The third daughter, Saori: She does all the housework, and she is like a personal maid. Second wife material: The eldest daughter Yurina, who watched Kauki and Saori being intimate.