: An urban legend in the city tells of a "killer of professional killers" who wears a traditional niwaka mask and takes down assassins regardless of their mission.

: The story follows an unlikely partnership between Zenji Banba , a private investigator who loves baseball and ramen, and Lin Xianming , a cross-dressing assassin who was originally hired to kill him but decided to become his bodyguard instead.

The series is a crime drama set in a fictionalized Fukuoka where it is rumored that are professional assassins.