A transfer student, Gilsoo, is attempting to quit school due to his history of severe bullying. However, the school president, after a confrontation, declares Gilsoo unprotected within the school's "fighting arena" system, marking him as a target for any violence. This leads to a brutal and humiliating attack by bullies, where Gilsoo initially resists but ultimately lashes out, forced to use his "gut" rather than skill. He is now facing a bleak future where his choice to not participate in the arena has made him a target for everyone.