The Mountain Hermit Kingdom is an island nation composed of hundreds of islands.
Honshu Island is quite large, featuring several feudal domains such as Izumo, Akina, Owari, Mikawa, Nagano, and Akibara...
Although they are called domains, the actual size of their territories is not that large—three or two of them together are roughly equivalent to a county in Luying.
The lords are called daimyos; you can think of them as something akin to princes. They are independent of each other, engage in conquests, and all nominally pledge allegiance to the imperial family.
The divine imperial family, "the Shinsu Clan," has its capital in Edo Castle.
"Rune Old Man" is the Shogun of the Bakufu, with tremendous power, almost the second in the nation under the emperor. This fellow's life is also full of legends, starting from marrying into a minor daimyo family and then gradually climbing to his current status.