Haruta strives to improve himself to win the heart of his childhood friend, Rio. However, while Rio maintains a supportive facade, she is secretly engaged in a passionate and illicit affair with Kaito, who takes pleasure in her betrayal of Haruta's feelings. Despite the deception, Haruta finally gathers the courage to confess his love, and Rio accepts him, leaving Haruta hopeful while remaining blissfully unaware of the truth.