If you're a demon slayer and you kill another demon slayer npc you can be punished by, being exiled or executed. If you kill ubuyashiki or the slayer corpse's mastery then you are forever banned from the slayer corps.
If you're a demon player and kill another uppermoon player then you take their spot, you can get challenged once a week, and there are requirements to challenge an uppermoon to their position.
you can be a hashira's tsugoku if they allow you to be one, and there should be requirements to it.
Hashiras can also retire whenever they please ( but are expelled from becoming one again )
fentseboy You’ve Reached Level 9