Tomoki comes from a family of second-rate thieves and is relatively normal aside from his skill in billiards. In order to become a first-class thief, he enrolls in the famous thief school Kaisei Higashioka Gakuen, otherwise known as Kaitou Gakuen. Surprisingly, he ends up in the same group as Ai, a descendent of the world-renowned thief Arsene Lupin, as well as her friends, revolver-toting Ooka and sword-wielding Koyomi. At Kaitou Gakuen, in addition to normal classes, there is a "hands-on stealing" class and subsequent test, which is full of ecchi traps. Will he be able to help them steal the targeted treasures with his superior decision making? How will things end up when their rival group Cats Pad and various detectives and other mysterious thieves also get involved?