500 years before the events of Demon Slayer, Muzan Kibutsuji escapes a gruesome death at the hands of Yoriichi Tsugikuni, the first Sun Breather and the inventor of all breathing styles.

We left the camp after we had inoculated the children for Polio, and this old man came running after us and he was crying. He couldn’t see. We went back there and they had come and hacked off ...