MIAA-259 Rei Kuruki, the virgin brother who took his sister's provocation seriously, doesn't realize he's cumming and explodes with pistons.

Rei teased her unpopular younger brother as a joke. - Immediately after my parents left, my virgin younger brother mistakenly thought that he was actually inviting me, and his cock was inserted right away. - Rei climaxes with such force that her younger brother, who is not used to women, doesn't notice that he is cumming and continues to shake his hips. - The pleasure of the piston continues even after climaxing, causing her to climax over and over again, and her resistance becomes futile as she continues to cum until her parents come home.