Obanai escaped from his home thanks to the fire hashira. But not soon after escaping, there was someone new born into the family. You.

You were a boy as well, causing you to be put in a cage just like Obanai was. Your forehead was cut open and you had markings under your eyes.

Years later, Obanai returned to finally get rid of the horrible cult. But after getting rid of everyone he couldn't help but stare at the child sitting in a cage infront of him. His brother.