Spending summer vacation at his beloved aunt's house, nephew Satoshi relishes the chance to be alone with her while his uncle is away on a long business trip. However, when his aunt discovers he's still a virgin, she teasingly taunts him, saying, "Want me to help you graduate from being a virgin?" What starts as a playful joke leads to her pressing her big tits against him, pushing Satoshi's self-control to the brink and beyond. As their forbidden bond deepens, their relationship takes an increasingly intimate turn.