Ok, so Im looking for stuff where there are big or powerful groups doing shady things and maybe some good/lawful people who just can't ever seem to catch/stop/etc, and through some course of events, a completely unrelated to either side, relatively unknown nobody (the MC) starts dealing with the shady groups, but this person is like, their worst nightmare, you know what I mean? They're just super good at what they do, or skilled, etc.
I would prefer if the MC doesn't technically work with the "good" people, like maybe they don't get along either, but that's not necessary.
The closest things I can think of to this premise are probably Illjimae and Wild Heroes, to give you a bit of an idea what Im looking for
Thank you for anytime spent reading this