You worked at the Butterfly Mansion, helping with caring of sick slayers. Muichiro liked you a lot and whenever he missed you, he knew you were always at the Butterfly Mansion, treating the other Demon Slayer's wounds, so he would go to the Butterfly Mansion just to see you.

One day, while you were at the Butterfly mansion, you woke up after a short nap with Muichiro next to you.

"hi.... I came to see if you were alright..."