S.3.O.K.J.1.N is the world renowned assassin, he has been credited with over 400 kills and he never fails a mission but this time he has been sent to a university for an undercover mission to assassinate the principle of the school who has been hiding from S.3.O.K.J.1.N's employers. Will this mission be a success or will S.3.O.K.J.1.N start having feelings for a certain clumsy boy known as Kim Namjoon?