A defenseless, busty sister gets fucked by her super-strong younger brother. She thought she was seducing her virgin brother, but... it turns out to be a surprise!

Mako, a daughter, comes to her parents' house to help with housework after her mother is hospitalized due to illness. While chatting with his father, his younger brother returns, but his attitude is somewhat distant. Mako, who was curious, looked into her room and found out that her younger brother had purchased a masturbation hole. Mako realizes that he is a virgin because she doesn't know how to use it, and teases her, but she is pushed down by the powerful adolescent powers... From that day on, he was fucked as his younger brother's sexual desire was what he wanted...