Upon confessing to their crushes, Marinette and Chat Noir both find out the hard way that those who hold the key to their hearts have affections for another. Rejected and blue, the pair find themselves in an odd sort of friendship, all while hiding the fact that they'd been the one to break the other's heart.

Adrien Agreste has never been an expert in controlling his emotions. When feelings for his classmate in pigtails begin to arise, he can't stop himself from seeing her any chance he gets—even as Chat Noir. Yet with all budding romances comes the inevitable (and quite unintentional) hurt, leaving Marinette to question her crush on Adrien and why a certain feline is making her blush.