A teenage boy's crush turns him into a phantom thief against his will, and the show treats that absurdity with complete sincerity. The romance doesn't wait in the background while heists happen, it is the heist, every stolen painting another chance to understand why his heart keeps betraying him. By the end, you realize the whole thing was never about the art at all. It was about a boy trying to steal back control of his own feelings.

Fourteen-year-old Daisuke Niwa's confession to his crush goes badly wrong, and that's when things get weird. Every time he thinks about her, his body transforms into Dark Mousy, a legendary phantom thief with a reputation for stealing priceless artwork. His mother, who knows exactly what is happening, starts making him commit heists. Daisuke has no idea why she wants these works of art. As he juggles school life, romantic feelings, and unwanted criminal activity, Daisuke discovers he's not the only one with a strange family inheritance. A classmate seems to share the same kind of ability, and that classmate may turn out to be his greatest rival, the one person he least wants to fight. The mix of action, comedy, fantasy, and romance keeps Daisuke's misadventures moving between laughs and a growing mystery about his family's secrets.