PIYO-020 "Siblings shouldn't marry is something humans arbitrarily decided", the twisted daily life of a sister who loves her brother too much and their forced insemination baby-making. Fuka Yusa

"Shinchan, I love you." The sister who dotes on her younger brother has been secretly having a sexual relationship with him without their parents knowing. The secret sexual acts between siblings hidden from the family. The brother's first experience. Sometimes directed jealousy towards classmates, and then to internal ejaculation. The sister and brother can't get married. But the two are connected even deeper. "If we have a child, I'll give birth to it..."