We know it's a strange relationship, but... Our parents are often away from home, so siblings Kanan and Yuzuru live almost by themselves. Yuzuru has become distorted due to lack of love from his parents, and has been a recluse ever since. His older sister Kanan spoiled her brother in place of their parents, but one day their relationship became strange. "Sis, I'm getting horny..." How should I respond as a sister and as a woman? After taking care of his sexual needs once, I started helping him again and again, and before I knew it, 10 years had passed... We've become adults, but our crazy relationship continues. Even to the point of intercrural sex. We tried never to cross the line, but we couldn't hide our soaking wet vaginas and our bodies that had become sensitive. Even when my younger brother secretly inserted just the head of his penis, I couldn't refuse...