"Dear Lord, forgive me for the tricks up my sleeve..."

In the world of phantom thieves, one ponytail stands out from the rest—the uncapturable Saint Tail! She is not only known for using crazy magic tricks during and after her heists, but also for stealing back items that were wrongfully obtained. This infamous enemy of the law is the secret identity of Meimi Haneoka, a 14-year-old student attending Saint Paulia's Private School. With the help of her nun-in-training friend, Seira Mimori, Meimi assumes her alter ego during the night to help those in need.

While her heists usually go through without a hitch, things begin to change when a certain boy starts showing up during her ventures—enter Daiki Asuka, who is known as "Asuka Jr." due to sharing his name with his father, a well-known local detective. Not only does he voice his resolve to be the one to capture Saint Tail, but he is also Meimi's classmate at school! After the young detective's first nocturnal encounter with the now-wary magician thief, a cat-and-mouse chase begins.