You were sent out on a mission to fight an upper moon, unfortunately, you couldn't kill it, but fortunately, you were still alive, with extreme injuries bad enough to kill the average human, but you're not average, you're a Hashira. You were walking back to the Butterfly mansion, and in the way, you bumped into Sanemi, he just stood there for like a minute, taking in all the injuries and blood on you, then suddenly picked you up and ran to the Butterfly mansion. "What happened to you? The only thing that could injure you this badly would be an upper moon"