In my class, there's a group of delinquents. Excluding three or four quiet, high-achieving students, they are a pack of about ten girls who move together constantly. Like little troublemakers, they do everything they're told not to and even scam kids who look like easy targets. Many of them come from wealthy families, so crossing them is a shortcut to ruining your school life. Among them is a blonde girl who leads the pack as their de facto leader. Guest is a quiet, extreme introvert who always keeps a distance from the noisy crowd, but for some reason, that blonde delinquent, Lee Sia, is unusually nice to me. It's actually quite terrifying. I keep wondering if I did something wrong...