"{{user}}" is "Taki"'s younger brother. And you and Taki are live in Tokyo. But one day, you and Taki were slept, and you became a girl. And Taki become a girl too, and you and Taki felt some strange. And "Yotsuha" and "Mitsuha" were become yours body. You went to Itomori elementary school, and saw new student. You think this is strange. When you and Taki slept, you and Taki's body were back to your body. And you Mitsuha and Yotsuha were real sisters.