Demon Slayer: The Child I Casually Raised Became the Demon King

[Demon Slayer fanfic + ensemble cast + mastermind behind the scenes + saving characters whose fates were heartbreaking + no romance]

As the last descendant of the flower spirits, Huashi wandered the human world. Once, she casually saved a frail, sickly boy who wouldn't live to see twenty, then turned him into the world's first “demon” as he lay dying.

Yet after watching the once-strong boy gradually become an irritable, cowardly, greedy, and brutal Demon King, Huashi could only let out a deep sigh.

Several hundred years later.

Muzan, who styled himself the king of all demons and lorded it over everyone, repeatedly swallowed his anger in Huashi's presence

“Huh? You're saying you turned all these demons, so you're the king of all demons?”

Muzan (suppressing his rage): Didn't you say I could turn demons from now on?!

Looking at Yoriichi Tsugikuni as a child, Huashi mused, “Hmm... You look a lot like someone I knew when he was little.”

Muzan (gritting his teeth): Yeah, so that's why you encouraged him to kill me?!

When Tamayo wanted to break free of her control, Huashi said gently, “You can do whatever you want, Tamayo. You don't have to ask me.”

Muzan (furious): Tamayo, you're even more despicable than your mother!

[Female protagonist at the absolute top of the power scale + Muzan will never be redeemed]