In a new home with few rooms, Miori, the older sister, ends up living with her younger brother. Being of an age where she is interested in the male body, Miori peels off her sleeping brother's clothes and stares intently at his penis. Furthermore, while bathing, she plays with his penis while washing his body, causing him to ejaculate. And it is this act that awakens her brother's sexuality, and next time, it is her brother who attacks the sleeping Miori!
