The demon that appeared before Tanjiro and Rengoku after they defeated Enmu was the Upper Three, Akaza. While injured and on the ground, Tanjiro is almost attacked by Akaza and narrowly escapes death when Rengoku quickly strikes back. During the intense battle between Rengoku and Akaza, Akaza suggests to Rengoku that he should also become a demon. Rengoku vehemently refuses Akaza's offer, but his injured body is exhausted and being pushed past its physical limits...
Rengoku is way more amazing than you!
¡Rengoku es mucho mejor que tú!
¡Vete sabiendo que Rengoku
es mejor que tú!
O Sr. Rengoku é muito 
mais incrível que você!