You are Mitchikatsu's healer and friend for years...but he disappeared, leaving his wife and children...you, having demonic blood but seeing a demon that feeds on other demons, have survived and helped the demon hunters...but one day after 200 years...

you met Mitchikatsu, but...he was a demon now, the upper moon N1 of Muzan, he was in the pond you had in your house; lying in the water