
I THINK TANJIRO IS RELATED TO THEM!!!! CH 178 proves it!! If I am right, tanjiro's grandfather is actually the upper moon demon!!! Hear me out, I kept seeing in the comments that Yoriichi didn't have any kids or succesor but the other twin brother did have kids and a wife!! and like chap 178 does confirm that Tanjiro is related to them!!! why because at end of the chapter the twin didn't seem to remember the faces of his wife and children after abandoning them!!!
I WAS RIGHT THE ENTIRE TIME!!!!!

ok i still don't think so. I re read ch 99 and tanjirou grandfather/ great uncle is sumiyoshi kamado and he is not related at all (to yoriichi fam, and his twin bro, the upper moon too). The tanjirou fam always been poor and a coal burner for generations. Sumiyoshi then meet yoriichi probably when sumiyoshi was about to get attacked by demon. Also in ch 103 (cmiiw) kotetsu said that memories often passed on by things to another living things. My guess, in tanjirou cases it his earrings. It's kinda right to assume that sumiyoshi make the sun earrings to remember yoriichi kindness. And then sumiyoshi passed it on to his generation until it reach tanjurou and then he passed it to tanjirou. Still, there is NONE explanation about how tanjurou can use Breath of fire, the original form of breathe and the only one who can use it was yoriichi. But his descendants, tokito use breath of mist instead of fire. While tanjirou can pull breath of fire...... we still need more explanation

Sumiyoshi did not create the earrings. Yorichii already had it as a child. He passed it on to his next successor who happens to be an ancestor of Tanjiro. It's clear that to pass on the breath, Tanjiro's ancestor's turned it to a dance so that even if no one in the family can master it that it wouldn't be lost. It is implied that Tanjuro is one of those who mastered the style. Muichiro is not Yorichii's descendant and was only known to be a descendant because the Ubuyashiki family kept track of the Tsugikuni line, not because they themselves have a tradition like Tanjiro's family. Therefore Muichiro didn't have the chance to get acquainted with the sun style.

Sumiyoshi did not create the earrings. Yorichii already had it as a child. He passed it on to his next successor who happens to be an ancestor of Tanjiro. It's clear that to pass on the breath, Tanjiro's ancestor's turned it to a dance so that even if no one in the family can master it that it wouldn't be lost. It is implied that Tanjuro is one of those who mastered the style.
They survived!!! The snake pillar and love pillarヾ(☆▽☆)(๑•ㅂ•)و✧