OMPIQUENT
In this particular What If:Tanjiro's ancestor, Sumiyoshi was the third brother of Michikatsu Tsugikuni and Yoriichi Tsugikuni, who hadnt become a demon slayer, Yoriichi in order to pass on his techniques to a kind and loving family teaches sun breathing to Sumiyoshi, his brother who had remained kind unlike Michikatsu who became a demon, as Yoriichi is a kind person and helped Michikatsu to develop moon breathing, to help pass on Michikatsu's technique too, teaches the moon breathing to Sumiyoshi, they pass on sun breathing as hinokami kagura, and by the birth of tanjuro, father of tanjiro, the tsugikuni name dies out and they adapt the kamado name, and they pass on the moon breathing in scrolls of kamado bloodline as a way to breathe that helps in using swords and fighting,