Who ruled Japan?
For most of Japanese history the honest answer is three people at once — and for a traveller, only one of them matters.
Ask who ruled Japan in 1750 and you can give three correct answers. An emperor sat in Kyoto. A shogun governed from Edo. And in the castle town you are actually standing in, neither of them was the one who collected the tax, built the walls, or decided where the road went.
English guidebooks tend to flatten this into "the samurai era". It is worth unflattening, because the third layer is the one that explains the place in front of you.
Layer 1 — The emperor reigned
The imperial line is the oldest continuous element of Japanese government, and for most of the last thousand years it governed almost nothing. From the Heian period onward, real authority drained away from the court while its legitimacy did not. That combination turned out to be durable: whoever held power still needed the emperor to make it official.
The clearest expression of that is the title of shogun itself. It was granted by the emperor. A warlord who had already won the war still went to Kyoto for the paperwork.
What this means on the ground: Kyoto is where the legitimacy lived, not where the decisions were made. The imperial sites there are a different kind of place from a castle.
Layer 2 — The shogun governed
Three shogunates ran the country between them, with long gaps and one catastrophic breakdown:
- Kamakura — from the late twelfth century to 1333. Historians argue about the start date; 1185 and 1192 both have a case.
- Ashikaga (Muromachi) — 1336 to 1573, from Kyoto.
- Tokugawa (Edo) — 1603 to 1868, from Edo, now Tokyo.
The gap between the second and the third is the interesting part. As Ashikaga authority collapsed, the country fell into the Sengoku period — the warring states — when neither the emperor nor the shogun governed much of anything and the provinces settled it themselves.
Which produces a fact that surprises most visitors: the two most famous unifiers were never shogun. Oda Nobunaga never held the title. Toyotomi Hideyoshi, who came closest to finishing the job, took the court office of kampaku — imperial regent — instead. Only Tokugawa Ieyasu took the shogun title, in 1603, three years after winning at Sekigahara.
Layer 3 — The daimyo held the ground
This is the layer that explains the castle you are looking at.
After 1600, Ieyasu reorganised the country into domains — han — and ranked them by rice yield. A lord qualified as a daimyo if his domain was assessed at 10,000 koku or more, one koku being roughly a year of rice for one person. Below that you were a bannerman, not a lord.
Ieyasu then sorted the daimyo by how far he trusted them, and the sorting is still visible on a map:
- Shinpan — branch houses of the Tokugawa themselves.
- Fudai — hereditary vassals who had been with him before Sekigahara. Often small domains, placed where they could watch a road, a checkpoint or a larger neighbour.
- Tozama — the outside lords, who had submitted rather than followed. Frequently the largest domains, and frequently the furthest from Edo. The Mori in Choshu, the Shimazu in Satsuma, the Date in Sendai, the Uesugi in Yonezawa, the Hachisuka in Awa.
That last list is not a coincidence, and it is not ancient history either. Two of those domains, Choshu and Satsuma, brought the Tokugawa down in 1868. Being kept at arm's length for two and a half centuries turns out to have preserved exactly the independence required to end the system.
The map under your feet is not the old map
Two things scrambled the geography, and both matter when you travel.
Lords were moved. A domain was a posting, not a homeland. Houses were transferred, promoted and demoted — the Sengoku house, to take one example, was moved from Ueda to Izushi in an exchange in 1706 and stayed there until the end. So the clan associated with a castle town depends entirely on which century you are asking about.
Then the domains were abolished outright. In 1871 the new Meiji government replaced the han with prefectures. Boundaries were redrawn and names changed, which is why the prefecture you are visiting usually is not the domain that was there. Yamaguchi is not Choshu. Kagoshima is roughly Satsuma. Ehime contains several former domains that had nothing to do with each other.
Where the shogunate's own men fit
One more group, because they are easy to miss and one of them has a drama coming. Below the daimyo threshold sat the hatamoto, the shogun's direct retainers, holding fiefs of under 10,000 koku and staffing the administration — finance, foreign affairs, the navy.
They were not lords and they were not warlords. They were the civil service of a military government, and in the 1860s they were the people trying to industrialise the country before it was taken apart. Oguri Tadamasa, who built the Yokosuka shipyard and was executed without trial in 1868, is the clearest case.
So who ruled the place you are visiting?
That is the question this site is organised around. Start with a person and the castles, graves, battlefields and castle-town inns follow from there — including, at the end of each guide, somewhere to sleep that is connected to the story rather than just nearby.
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Oguri Tadamasa Draft
Oguri Tadamasa built the shipyard that outlived the government that executed him. A guide to the Yokosuka and Gunma sites, and where to stay nearby, before the 2027 NHK drama arrives.