I'm in the Hokage World, but the Demon King Muzan Lives Inside Me

[Hokage, multiple heroines, mostly everyday life, invincible]

After transmigrating into the Hokage world and suddenly gaining an immortal body, Shifeng Jing was delighted.

But what was this about suddenly having Muzan Kibutsuji from next door’s Demon Slayer inside her body?

And why was Muzan only the female version?

It was so annoying having to listen to this obnoxious boss ramble every night. I really ought to teach you a lesson, Muzan.