After I got married and moved into my husband's house, I started living with my husband's high school sister, Mitsuki. But sometimes I was worried about the way Mitsuki looked at me. And then, a sudden kiss in the morning. I thought it was just a precocious girl's prank, but he told me that he had been thinking that it would be nice if a sister like me came to live with him since he was dating my brother before we got married.