By using tarot cards as a "learning diagnosis System," the heroine can create an actionable study plan or pinpoint gaps in someone's knowledge every time she turns over a card. But each reading comes with a compulsory "equivalent exchange": she must teach the plan she draws to someone else without holding anything back, or the cards become ineffective for three days. Then she draws the card with the harshest restriction of all: she must help the worst student in her class improve. As she racks her brains to "motivate" the school bully to work through practice problems, she also has to deal with sabotage from his gang of friends, who can't stand her "playing fortune-teller," and the increasingly high scores on her own math tests.
