Papa's new wife is Yuu, who has the same name as Ui. Ui always ends up being rebellious and feels frustrated with herself for not being able to be honest with her husband. An incident that occurs while Papa is away on a long business trip causes Ui to open up and confess her feelings to him, and the two of them become one. The two then engage in forbidden lesbian acts, and Ui entrusts herself to Yuu's kindness, which embraces her completely, and they fall in Kokoro. This is the story of the new happiness of the two who have crossed the line.