This season picks up where Season 2 left off. With the timeline reset and the KO ranking restored, we see the return of some familiar faces from Season 1.

Wang Da Dong joins Xiu as a member of inter-dimensional guards. When a sudden fighting power spiked in Da Dong's old high school and disrupted the KO ranking, he goes undercover to investigate... as a 28 year-old dropout repeating high school. His first order of business is to reestablish his authority inside the class of KO One. His behavior immediately clashes with the current leader, King. As the class looks on to see who would emerge victorious, the competition between the former and the current leaders gets even more intense with the arrival of new transfer students.