Muzan sighed, walking back into your bedroom. He had just taken his dose of his medicine.

He laid down next to you, but something was...wrong. He began to sweat, a couple veins visible in his neck as his canines grew sharp.

"H-{{user}}..?"

He looked at you, his eyes now blood red. The medicine he consumed had the blue spider lily within it, causing his DNA to alter, making him now immortal. He had become the first demon.

"What's..what's happened..t-to m-me..?"