Kamado siblings are descendants of Kokushibo

 My theory is that the Tokito twins and the Kamado siblings are in fact both descendants of Kokushibo.

This theory came on a morning shortly after finishing the manga in the first two weeks of September 2026. It mainly started out as a simple thought. But then I thought about it, the more it started to make sense.

First there was the mangaka, which said that they, Tokito twins and the Kamado siblings, were related. Yet I could not think about how. After all, even though most assume that Tanjiro and Nezuko are the descendants of Yoriichi, but the manga clearly shows that his wife and child were killed, therefore a genetic dead end. So the only way that they could be the descendants of him is if he had a secret family, but no. That would not be something that he would do.

So, how is it that Tanjiro and Murichiro's father look similar? Well, that is where Kokushibo comes into the picture. He is the identical twin brother of Yoriichi who had a family (that was not named) which he abandoned to become a demon slayer before he became a demon and upper moon 1.

 Anyone that knows a thing or two about how identical twins are formed knows that the fertilised egg breaks in two forming two separate babies making them genetically almost 99% identical, as both inherit the same genes. Which leads to them having the same face, eyes and hair, with only small physical details that can differentiate between the two.

So you have someone that is identical to Yoriichi, that has almost identical genes, that has a living family that was unnamed that could pass on his genes to another generation. 

Now back to the unnamed family, now here’s a what if; what if that unnamed abandoned family was none other than the family that Yoriichi visited and gave his earnings to? What if the reason that he was even there was to meet his nephew and tell him all about what happened to his father? What if the reason he even gave that family his earnings was because they were family? 

After all, if you think about it, it makes sense as to why Yoriichi was there and why Tanjiro’s ancestor, that he was seeing through the eyes of, looked similar to Yoriichi. They were uncle and nephew! It would even explain why Tanjiro, with his hair long, looks almost identical to Yoriichi, why Mr Tokito, the father of the Tokito twins, looks almost identical to Tanjiro, they are both the descendants of Kokushibo back when he went by the name of Michikatsu Tsugikuni.