Every month, 25 students in Class 5, Grade 2 of a high school vote to rank everyone in the class through a pyramid game. With the lowest grade, F, becoming a legitimate target for bullying. New transfer student Seong Su-ji quickly became a victim of bullying. In order to figure out the secret voting rules and break through the situation, Su-ji launched a wonderful battle of wisdom and psychology. She found that the person who established the class pyramid game was the princess Bea Harin with a wealthy family background. Su-ji therefore trying to destroy the pyramid game.