Killer Is Dead includes such technology as lunar tourism and cybernetic enhancements. The main character is an executioner named Mondo Zappa (voiced by Ryotaro Okiayu in the Japanese version and Patrick Seitz in the Western version) who receives jobs from the Bryan Execution Firm. This firm, run by a cyborg named Bryan Roses, tasks Mondo with killing dangerous criminals and assassins from around the world. Mondo wields a sword with his right hand but his cybernetic left arm can be converted into many different weapons, including guns, drills, and other objects. Although Mondo travels the world as part of the game, Suda calls it a “personal story” of “a man who doesn’t show himself much in the public world but still worms his way into society and mercilessly eliminates the evil dispersed in it”.
“Love and execution” and “how far can you protect someone” are also central themes of the story.
The game begins following a deranged former executioner named Tokio who has kidnapped a girl and is being hunted by a katana-wielding man who looks like Mondo. Tokio calls him “the darkness” right before he is killed. It then flashes forward two years to the modern day where Mondo is accepted into Bryan’s execution agency following his assassination of the former executioner in his place, who had also been taken over by a dark force and was deemed unfit for his job. This man, Damon, warns Mondo about the perils of the job and that he may also fall to the dark side.
