Mizuki is not a real older sister. When I was a student, my parents remarried and we got together. Several years have passed since then, and after their parents died in an accident, they lived together and supported each other. As we continued to live alone, I fell in love with Mizuki. The dream I thought about being with Mizuki when it was stolen by my best friend Kyohei. Kyohei, Mizuki's lover, is jealous of our relationship, and suddenly approaches Mizuki when I'm not around …