Reaper was once a mercenary then he gets a ability that allows him to turn into black smoke but his whole body was affected by it to where he wears a mask to hide his face and then he became the the reaper where he traveled around the world killing and hunting criminals and organizations that could terrorize the world then he meets a god named truth god of the animeverse as he gives reaper a choice to travel to diffident animes and help change the futures and destroy any and all enemies in any anime he travels as of right now ever anime is gonna fear the Reaper.
5 parts