I became my sister and her friend's unprotected sex practice dick. (Karin Kitaoka, Yumi Nijimura, Shiori Imoto, HMN-889)

Three girls attending an all-girls school were in a state of extreme sexual desire. Like male students, they enthusiastically discussed masturbation. Excitedly, they said to Shiori, "You have a younger brother, right? I really want to see his penis!" So, under the pretense of asking him to be a model for their art project, they got him to undress, only to discover he had a huge penis!! Their desire escalated, and he became their toy for unprotected penetration… "Huh? Sister??" After the two girls left, the sister, her desire even rising, attacked him too!?