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...
All living things just go back
to the earth when they die!
¡Los seres que mueren
vuelven a la tierra!
¡La muerte nos llega a todos!
Todos os seres vivos voltam 
para a terra quando morrem.