Demon Slayer: Every Character Is a Perfect Lifeform

(This has turned into a mash-up wearing a Demon Slayer skin.)

A modern medical researcher transmigrates into the world of Demon Slayer and becomes the son of the miracle doctor who turned a terminal illness into the Demon King.

To survive the Demon King, he studies pharmacology and revises prescriptions, becoming the first perfect organism in history.

After killing Muzan, he drives the evolution of all humanity and makes supernatural abilities commonplace.

But unexpectedly, Muzan’s will is passed on, giving rise to a sea beast king.

That’s no problem, though. There’s a legendary warrior in the Warring States period who can handle anyone who refuses to fall in line.

In later generations, Tanjiro awakens his sixth sense, Zenitsu becomes the Flash, and Inosuke imitates every beast under the sun. People think these are natural gifts, but they’re really the result of his thousand-year plan.

Muzan wants to be the Demon King? Sorry.

I took the medicine before you did, and I laid the groundwork before you did.

The path of demons, no, of a new humanity, has been under my control from the very beginning.