Mizuki and I are not actually siblings. We met as stepchildren when our parents remarried when we were students. A few years later, our parents died in an accident, and we lived together, supporting each other. As we continued living together, I began to fall in love with Mizuki. But my dream of staying together with Mizuki was snatched away by my best friend, Kyohei. Kyohei had feelings for Mizuki, and was jealous of our relationship, so he got close to Mizuki while I was away...