Demon Slayer: Asura

After arriving in the world of Demon Slayer, Xingchen becomes a demon to survive, then builds an incredibly powerful organization to stay alive.

He develops the Blue Spider Lily himself.

He creates new Breathing Styles himself.

He invents powerful Blood Demon Arts himself.

When Kibutsuji Muzan discovers the organization,

he realizes it has grown so powerful that he has no way to fight back.

(The farming phase is skipped. The story starts ten years after farming.)