JUQ-128 My beloved sister-in-law, who raised me single-handedly, was cuckolded by my worst friend... Ai Mukai

Ai-san and I are not really siblings. When he was a student, Ai was the stepchild of his father's remarriage. A year later, after my parents passed away, Ai-san became my parent. During the days we spent together, I began to feel a special love for Ai-san, my only family member. Just as I vowed to make Ai-san happy in the future, my bad friend Shinji approached our family.