Yumi, who married a man with a son, found that her husband's stepson, Ryota, had harbored feelings for her from the moment he saw her. As he began to see her as a member of the opposite sex, Ryota distanced himself from Yumi. Eager to deepen their relationship, Yumi took even better care of him... A virgin, Ryota could not resist Yumi's allure and engaged in self-pleasure, almost licking her underwear. Yumi, shocked yet excited, witnessed the scene. Then, in a gentle voice, she whispered to Ryota, 'Do you want to know about adult kissing?'