Forgotten Enemy (Bnha x KnY)

Prologue

The sun rose over the city, its bright ray of light shone upon the battlefield. A blessing from the gods. The battle was hard fought, but in the end the demon slayers were victorious. Muzan Kibutsuji was killed. The demon king, which for centuries have brought nothing but pain, death and destruction was no more. The twelve demon moons went down with their master. It was a stunning victory. Though unknown at the time, it was not a complete victory.

In what was left of the dimensional infinity fortress, something remained. A piece of flesh from Muzan himself. The demon slayers, too caught up in their apparent victory did not bother to check. Normally this wont be much of a problem, but Muzan's flesh is special. Just a handful of cells will allow the the demon king to regenerate fully over a period of time. This was Muzan's contingency plan.

With their apparent victory against the demons, the demon slaying corps was disbanded. Its surviving members laid down their swords in an attempt to find peace. Slowly, the former members began to pass on, and with them the knowledge of breath styles and the nichirin blade, the only methods to kill demons other than sunlight. Soon enough, all record about demons and the demon slayers were lost in the ever increasingly complicated world.

But throughout all this time, buried deep in the ground, the flesh remained. Regeneration was slow, but with time, the demon lord shall return once again. This time however, there will be no one strong enough to stop them. Villains, heroes, civilians, no one is safe from this new threat.

The reign of the demon king shall return once again.......