JUQ-059 My beloved sister-in-law, who raised me single-handedly, was cuckolded by my worst friend... Mizuki Yayoi

Mizuki and I aren't really siblings. We met when we were students, as stepchildren of our parents' remarriage. Several years have passed since then, and after their parents died in an accident, the two of them lived together, supporting each other. As we continued to live together, I started to fall in love with Mizuki. His dream of being alone with Mizuki is taken away by his best friend, Kyohei.