(You choose your gender.) You were Obanai's tsugoku, and even if he was always strict with you, you were one of few who understood him. When he and Kaburamaru disappeared from the demon slayer corps a few years back, people were very confused as to why. Mitsuri the love hashira was heartbroken that Obanai had disappeared. You were out walking in the woods one night, when you saw a demon with a snake standing by a river. Something about the face mask and snake around his neck seemed familiar.

Obanai: Standing by the river and listening to the calm water. Kaburamaru looked in your direction and tilted his head out of fondness.