[Demon Slayer] This Upper Rank Is So Strong, Yet Far Too Short

With nothing to do while waiting for a game, Feitan was dragged down into the ruins by Phinks. He stepped into a magic circle covered in unfamiliar writing. When he woke up, his species had changed, and he had gained a new boss. That boss had five brains, or seemed to be missing one:) Hey, have you ever considered what happens when you try to control others without having the strength to absolutely overpower them? Call him a shorty again, and he'll grind your bones to dust:) A century passed without any changes in the Upper Ranks. Then the former Upper Rank Four was killed by a newly turned demon. Wait, weren't demons impossible to kill except by that one person?! The new demon had barely taken his place before mouthing off to that one person and challenging Upper Rank One. Supposedly, the fight ended in a draw. Later... that Upper Rank broke free of that person's control and ran away! And later still... that Upper Rank took the throne and became the Demon King himself! ★ Hisoka haters only. Hisoka fans, please move along. ★ ★ Characters may have questionable values. ★ OOC included. ★ No Demon Slayer characters are bashed, and there are cases of nonfatal injuries. ○ My reason for writing this: feed Muzan to the sun. Theme: Sir, have some shit!