A Demonic God Made of Coal and Flower Petals
6 parts Complete Proceed with caution. Manga spoilers! There are pretty mild, but still!
This is a AU story where Yoriichi becomes a demon!
A warm liquid spilled in his mouth with a rush followed by a burning sensation searing his insides from the tip of his tongue past his stomach to the very tip of his toenails.
Blood.
Demon blood. Muzan's tainted blood.
Oh Michikatsu, my dear older brother, what have you done?
*
Kokushibo traps his newly, unwilling demon brother inside a cave while he goes off on his own to train even harder so he will win their next match. However, Kokushibo does not check the cave often.
Therefore when a young Kamado Tanjiro happens upon a trapped demon inside the mountain, he mistakes him for a god and places offerings inside the cave.