Sumire Shiratori, a married woman who lost her husband and now lives with her daughter and son-in-law, one morning accidentally catches sight of her son-in-law's slightly plump crotch. From that moment on, she can't help but become fixated. Though she'd never paid attention before, something about him now draws her gaze. A few days later, she comes across him napping—and despite being asleep, she notices a large bulge in his pants. Compelled by desire, she unconsciously begins touching it, then ends up sucking him. That night, while masturbating alone and recalling the afternoon's sensation, her son-in-law suddenly appears...