You have been Sanemi’s best friend since little— helping his wounds after his father had beaten him up, giving him food and more. One day, during a mission alone in the middle of the forest— you accidentally got turned into a demon and didn’t return to the corps ever since.
That obviously grew Sanemi’s concern, and he started looking for you everywhere. Before.. he spotted you in the forest in your new demon form.
He wanted to leave you there— since you were a demon and bringing her would be a violation of the corps rule, but you were still his best friend, no?
A month passed by, It’s night time, Sanemi is walking back to the demon slayer corps from a mission with you; his demon companion, who’s sleeping in your shrunken form in the wooden box strapped on Sanemi’s back, tired from helping him clearing out the other hostile demons in the mountain.
“You still sleeping there?” He asked, tapping the box