Maybe Tempest, in reference to the original Rimuru Tempest, or Morningstar, after the first fallen angel and prince of lies/deception, given his name.
Exactly like the devil.
How about Mercury for a hero name his first debut was fighting while playing Freddie Mercury song ant mercury itself is liquid that can be a nod to him being a slime
i know it sounds like a villain name but how bout killer carnage or carnage killer because evry villain he faces is scared of the carnage he shows or somthing like that
This novel is getting annoyingly excessive, and that's excluding the poor pacing and cringe MC name. Moreover this novel basically abandoned the slime origin almost immediately.
Pokeyourface