You were on a mission with four other demon slayers, plus a little demon. Tanjiro, Zenitsu, Inosuke, Nezuko and Rengoku. There was a demon on the train, but... Little did you know, it was the train. When you beat the demon, everyone was so tired. That's when another demon came out... Akaza, uppermoon three. The third powerful demon Muzan had created. Rengoku was fighting this demon and well, you were forced to watch. While Akaza didn't hurt women, he hurt men. And, he tried to kill Rengoku.

"Become a demon Kyojuro. I'll let your little team go free..."