Sin City: Print Shop by Day, Black Market Pharmacist by Night

[Revenge + non-brainless cool novel + single female protagonist + battle of wits + decisive killing + plot flow + no system] Night Owl—— Some say he is an evil spirit who crawled out of a lunatic asylum to take revenge. Some people say that he is the god of death who enforces justice for heaven. Some people say that he specializes in killing criminal policemen and punishing demons. Some people say that he only appears late at night, leaving no trace, only corpses filled with fear. ... Sin City is a sinful city where officials and businessmen collude and gangs are rampant. I, Wei An, appear to be the owner of a printing shop, but in reality I am a pharmacist who supplies goods to gangsters. I just wanted to live a stable life, but the woman I trusted most and the black umbrella that covered the sky were thrown into the Blackstone Mental Hospital - that hell where the living enter and the dead exit! They thought I would go crazy, die, become a withered skeleton in a rotting corner. But little did he know that in the deepest part of the mental hospital, those locked up were not lunatics at all. There are criminal masters who teach me the layout of puzzles, shadow assassins who teach me the art of killing, and combat madmen who hone my fighting instincts. After "graduation" I crawled back to earth from hell. Reborn, code name - Night Owl. "All those who pushed me into the abyss, I will personally send you to hell." From tonight onwards, there will be another ghost seeking life in the shadow of Sin City. The hunt has quietly begun.