The Mifune and Satoda families, who have yet to make a promise of engagement, have lost their parents, and 'Karen', who is training to be a bride at the Satoda family, realizes that her fiancé, Ryota, has awakened to his sexuality. Ryota, flustered by Karen's large breasts, finds himself drawn to her. Seeing this, Karen feels a tender love for him and becomes addicted to the pleasure of taking the innocence of boys who know nothing...
