I'm by no means well-learned when it comes to this but it seems Ieyasu was either issuing and assigning the territory of various daimyo who fought alongside him at Sekigahara, mainly the Toyotomi daimyō and he was in charge of negotiations between those who joined the opposing side at Sekigahara like Shimazu and Uesugi and the Toyotomi Government to re-assign their territories now that they had been reduced significantly, one example would be how the Toyotomi direct land holdings in Settsu Province had been given to Pro Tokugawa daimyō. I'm not Japanese but ive learned quite a bit so hopefully you can translate this however I could expand on this if you would like.