Takumi's mother Yukie plays volleyball, after a day of hard practice and so much sweat she would take a bath as soon as she arrives home. One day Takumi knowing how sexy his mother looks in her uniform, in that bloomer and shirt, he decides to secretly go to the bathroom at take a smell of her mother's bloomer and shirt, while he was fantasizing about her mother he starts hearing strange sounds.... his mother is MASTURBATING, he can hardly believe he is experiencing such amazing event, he starts masturbating as well.

After that and before her mother is done with her bath he takes Yukie's sweaty shirt and bloomers to his room, he then wears them an starts masturbating, suddenly his elder sister Mika enters his room after hearing some noises, after knowing that her little brother is masturbating thinking in his own mother Mika...