Mizuki is not a real sibling. When I was a student, my parents remarried and we met each other. Several years have passed since then, and after their parents died in an accident, they lived together while supporting each other. As we continued to live alone, I began to fall in love with Mizuki. The dream that I envisioned to be with Mizuki as it is is stolen by my best friend Kyohei. Kyohei, who likes Mizuki, is jealous of our relationship, and suddenly approaches Mizuki when I'm not around...