Takashi lives in Tokyo, staying at his aunt Yukie's house as a lodger. He has always admired Yukie for her kindness toward him. One day, as Takashi opens the bathroom door to take a bath, he finds Yukie climaxing from masturbating. Both are shocked and flustered, unable to hide their surprise. But when Yukie whispers, "I'm... lonely," her words strike deep into Takashi's heart. His long-held admiration instantly transforms into reality. No longer just a lodger, Takashi becomes someone who intimately enters Yukie's life, drawn into a new, forbidden relationship.