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...
Those who were born
blessed with more gifts than others
Aquellos que nacen
con más talento que los demás
Quienes nacéis
con más talento que los demás
Aqueles que nascem naturalmente abençoados 
com mais talento do que os outros…