alright so, the demon slayer corps is a secret, highly militarized organization that specifically works to kill demons and their allies. this includes humans working with demons, allegedly or not. at the end of season one, the hashira were debating on killing tanjiro and guiyu for protecting nezuko and obstructing demon slaying. alot of them, including fan favorites rengoku and tengen were all for cutting their heads off then and there, without a trial. the others didn’t seem to care either way. and the fact that they didn’t seem too hung up on the option of executing one of their own implies they have had to do this more than once, and that tanjiro wasn’t the only case of this happening. my point is that they -specifically the hashira and the master- act as acts as judge, jury, and executioner for humans in league with the demons.
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well, remember those human minions of enmu’s in mugen train? they were working with demons, a crime punishable by death according to the demon slayer corps, and because they’re a secret organization with an insane amount of power they can pretty much do whatever the heck they want. now rengoku’s dead, ( 🙁 ) inosuke probably wouldn’t care, zenitsu doesn’t remember, and tanjiro wouldn’t report them, but if other members of the corps investigated the incident it’s likely that the human servants of enmu were found out by the corps and executed, them being manipulated or not. the train conducted even directly harmed a demon slayer.
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it’s possible that this punishment only exists for demon slayers as their actions would be considered a direct act of betrayal instead of the acts of manipulated innocents, but this is all speculation anyways, and I think it would have been interesting if rengoku survived, had to kill the human traitors, and the see how that would have impacted Tanjiro’s view of him and the corps as a whole (though he is a noticable expection as he doesn’t share all of the corp’s beleifs anyways, such as all demons being evil and no sympathy spared for them)
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