殺し屋事務所のボスの息子・丸岡マルクは、小学4年生のエリート育ちな殺し屋。ある日、依頼された標的は、「伝説の殺し屋」で己の立場を疑問視し始めてしまうのだが……!?
Born to the boss of a hitman agency, fourth grader Mark Maruoka spent his whole life being groomed into an elite assassin. But when his latest target turns out to be “the legendary assassin,” Mark starts to question his own role in this world of shadows…?!