Funouhan

Funouhan (不能犯) is a manga written by Arata Miyatsuki and illustrated by Yuya Kanzaki.

Plot
At a certain park, there is a mysterious man, who has red eyes and a black suit, that people can go to and request him to kill someone. His assassinations can never be blamed on him because he takes no illegal action. His strength is in the power of suggestion and the arrangement of events. He accepts these requests, all the while privately mocking the foolishness of those whose unwise wishes he grants.