A man posing as a private tutor gives his student a so-called fatigue-reducing supplement, secretly laced with an erection-enhancing drug. He maintains a calm demeanor, pretending nothing is amiss, but gradually succumbs to temptation through accidental panty flashes, bra slips, and blowjobs, pushing his sexual desire to the breaking point until he finally engages in sex. Shortly after, his younger sister walks into the room unaware of what just happened, only to witness the aftermath. Confronted by her, he expects anger and accusations—but instead, her hands slowly move toward her still-erect brother's crotch.