During summer vacation, a virgin visits his brother in Tokyo from the countryside, only to learn that his brother will be away on business for four days. His brother’s live-in girlfriend agrees to look after him, beginning an unexpectedly intimate stay together. Her revealing clothes and casually provocative behavior overwhelm him, whether she means to tempt him or simply feels at ease because he looks just like his brother. He admits that he desperately wants her, and she agrees on the condition that he keep his eyes shut. Too excited to control himself, he turns the next three days into a sweaty marathon of relentless pounding, reverses their positions, and finally ejaculates inside despite her warning not to.