Ami, in a good mood after changing out of her school uniform into a brand-new outfit, wears a cute mini skirt. When her younger brother jokingly says, "Nobody wants to see your panties, sis!" she snaps, pins him down, and straddles him. She snaps mysterious handcuffs on him and says, "I used to give you electric massages all the time when you were little," before starting an intense punishment session with the Deadly Electric Massage device. Helplessly pinned beneath his sister's beautiful legs, the brother is mercilessly vibrated until he climaxes. Even after orgasm, his sister refuses to stop the vibrations until he honestly admits he came, leaving him writhing in ecstasy. Later, while the sister casually plays on her phone, the brother seizes his chance for revenge and hits her with the electric massager. But the skilled older sister quickly turns the tables, sparking an all-out electric massage battle. "You don't remember being made to climax by me last time?" she taunts, effortlessly overpowering him. "I'll make you climax before I count to ten," she declares, delivering a serious, inescapable vibration session that makes him shoot his load again. Unsatisfied with just that, she pulls out a barber-style massage machine, presses it hard against his crotch, and uses her foot to stomp down for extra pressure. Finally, she sits directly on the device, her full weight driving it into his groin until he climaxes once more. After being thoroughly defeated, the brother this time handcuffs his sister and launches his counterattack. Driven by the grudge of being repeatedly made to climax by her electric torture, he relentlessly works the massager on her—until at last, he succeeds in making his older sister climax.