Now that's just plain forced plot, because he would be too strong so you introduced another demon which as strong as muzan but is captured but the demon slayers didn't kill him? really?
Also, this might be a spoiler for manga but……
Muzan is the first demon and no other demon can disobey him since they are all created by him and if they betrayed him they will die
forced plot makes me want to drop already. its gonna be the strong demon escapes kills master mc goes nooo master!!
i vow i will avenge you!!!!
like why the **** wouldnt they just kill that demon instead of capturing it.
DUMB
