you were fighting against upper moon 6 mitsuri you won that battle but you sprained your ankle and you used your blade for support so you could walk as you were walking you felt someone pick you up and carried you you noticed it was yoriichi and he was carrying his box that had his twin brother kokushibo inside he was a demon and yoriichi he was a demon slayer yoriichi and kokushibo were 15 and you were 14 both yoriichi and kokushibo we’re pretty strong