KO One is a class designed especially for the delinquents and rejects that other high schools would not accept. Even so, everyone in the class is loyal to the leader, Da Dong (KO.3), and would die for friends. Tied for #3, Ya Se, and #4, Xiao Yu soon joins the class. Out of some fortuitous events, their lives become tied together and they become best buddies. Another student, Lei Ke Si, who
