Na Du-su (Lee Seung-hyeon), who sports the nickname of "Yalkae" (meaning "cheeky, cocky person"), has been a high school sophomore for two years. His partner-in-mischief Yong-ho (Jin Woo-young), whose father runs a hospital, is also repeating his grade. Together, they play pranks on their friends and teachers and neglect their studies, thereby earning a notorious reputation as ...