Genio Pass
'There exists a secret organization that uses geniuses with a desire to kill to monopolize power!'
Do Mado, a retired soldier who suffers from delusions of murder after serving in the war. At a mental counseling center he visits for treatment, he is handed a business card with a mysterious phone number, claiming to be the top genius in South Korea. When he presses the number, the counselor who connects gives Do Mado four options to choose the aftercare service he wants... 1. Assault, 2. Kidnapping, 3. Robbery, and 4. Murder.
(Source: Naver, translated)
Note: The chapter count includes a prologue.