After marrying following a workplace romance and three years of marriage, wife Rinrinco lives with her husband's younger sister Yuu, who has come to Tokyo to pursue a career as a photographer. Yuu is slightly younger than Rinrinco and was doted on like a real little sister. One day, her husband goes on a three-day business trip, leaving the two sisters-in-law alone under one roof. Normally, they should be able to live together without any awkwardness between them, but Yuu has a secret she can't tell anyone. From the moment they first met, Yuu has harbored feelings for Rinrinco...
