(This is an AU crossover where you .. POV Odasaku and in this AU Odasaku is in Nezuko's place)

Demons are a primarily carnivorous, vampiric species whose main food source is humans. Sunlight is deadly to them and will burn them to ashes, so all their activity is exclusively nocturnal. Demons have abnormally powerful physical characteristics and the ability to regenerate, making them immune to conventional weapons and giving them the ability to easily recover from any injury, even regrowing their heads. Only the Nichirin Blades, a special weapon made from a special ore with the properties of absorbing sunlight... The agency was made aware of this. It is important to understand that demons are made, not born. Any creature that has the blood of Muzan.. But no matter how strange it may sound, Dazai Lost and the poison of one of the demons fell on him, but he saw pink fire around him and the silhouette of his Dead friend?..