Keisuke Shinozaki returns to his grandparents' house for summer break and finds his mother's much younger sister Yuuka waiting there. He has always adored her — kind, smart, and beautiful — but the news that she is now engaged is a shock. Longing and Guilty Pleasure follows Keisuke as he confesses his feelings rather than let her go. Regret and Lust follows an older Keisuke who decides to take her back, despite the blessing he once gave her marriage. Two stories, one transforming relationship.