Personally, I'm not very knowledgeable on medieval to early-modern Japanese history, and was curious, what did the average person think of the fact that the shogun was often the de facto ruler of Japan? I'd imagine that it wouldn't be something that they would think (or care) about too often.
Additionally, considering the status of the Emperor as the "proper" (perhaps not a good term here) ruler of Japan, how was the Emperor's lack of power justified by the de facto rulers or nobility? Besides any notable wars in which it came up, was the topic of right to rule ever debated in texts? Or was the role/scope of the Emperor's position one that just became accepted over time and was just thought of as normal?
As far as time frame, I'll leave it up to whoever wants to answer.
[Reposted as asked]
Part 1 of 2:
Note: The English-language convention for ordering Japanese names is usually to put given name first, then family name. However, the convention for ordering pre-Meiji historical names is to keep them in the original Japanese order, family name first, given name second. This keeps us all on our toes. As this reply features both modern Japanese historians and long-dead historical scholars, I thought it might be worth mentioning what’s going on there. I’d love to just write all Japanese names in one format, but it’s best to replicate how you’ll find them in English-language sources.
Before I wrote up this answer, I searched Ask Historians for answers to this and related questions. The results were a mixed bag. A lot of the older Ask Historians answers about the relationship between emperor and shogun in the Edo Period (1600-1868) were obviously heavily influenced by a Meiji-era narrative of Japanese history.
However, /u/shakespeare-gurl wrote a really good answer on the earlier history of the relationship between shogun and emperor, which would be a great place to get your bearings.
So, now on to the Edo Period 1600-1868! The Tokugawa are the shoguns ruling Japan from Edo (today Tokyo), the Emperor and his court are tucked away in Kyoto not ruling anything. What did the ordinary person think of all this? Did they think about it all?
It is obvious to sensible historians today - and it was all to apparent to the Meiji regime’s leaders - that during the Tokugawa period the common people had neither a strong sense of national identity nor a clear image of the emperor as the Japanese nation’s central symbol.
Takashi Fujitani’s book Splendid Monarchy is a seminal work which details how much of the Imperial institution in Japan is "Invented Tradition." According to Fujitani, the rituals, trappings, language, activities, and understanding of the Japanese Emperor and his role today are in large part post-1868 creations by politicians.
“Invented Tradition” is a concept which actually had its own Monday Methods discussion here on Ask Historians a few months ago: Monday Methods: Eric Hobsbawm and the Invention of Tradition.
To quote Hobsbawm’s definition of the concept:
Invented tradition is taken to mean a set of practices, normally governed by overtly or tacitly accepted rules and of a ritual or symbolic nature, which seek to inculcate certain values and norms of behavior by repetition, which automatically implies continuity with the past. In fact, where possible, they normally attempt to establish continuity with a suitable historic past.
In the case of the Emperor of Japan, the rules and rituals around the person of the Emperor were designed to hark back to the prehistoric days of Japan, the mythic past of the gods. Fujitani’s thesis is obviously unpopular in some Japanese nationalist quarters, but it really isn’t debatable that there was a lot of innovation involved in the creation of the new Imperial institution and the setup of State Shinto. It’s also true that the Imperial family of Japan does date back centuries, and they did always claim descent from the gods. There are authentic centuries-old traditions and “invented traditions” here to be untangled.
Fujitani’s book is about how nineteenth century people created such “invented traditions” around the figure of the Emperor, but it begins with a short review of what we know about the average person’s understanding of the Emperor during the Edo Period. Which is really not too much. No one was writing down the insights of poor farmers or fishermen in the backcountry. But we can say that, at the most extreme, some commoners in Tokugawa Japan didn’t even know the emperor existed.
Suzaki Bunzō, born on Amakusa Island (Kumamoto Prefecture) into a long line of fishermen, and a centenarian at the time he was interviewed in the early 1960s, remembered that one of the major reasons for the reluctance of villagers to become recruits to fight against Saigo Takamori’s rebellion in 1877 was that they were not sure who the emperor was. Elderly women were saying, he recalled, that “even though it’s said that the emperor’s taken the place of the shogun, what kind’a person is he (dogan hito ja)? Must be the one in the kyōgen play who wears the gold crown and the full-sleeved robe with gold brocade.” (- p. 7, Fujitani)
However, the Emperor did play a role in religious belief and ritual throughout Japan. Fujitani notes that the Emperor in peasant beliefs was often a figure of legend, overlapping with the “marebito” - supernatural sacred beings who appear in a community and work miracles, such as ending droughts, healing the sick, ensuring a good harvest. (p. 9, Fujitani) Belief in the Emperor as a supernatural protector did not mean any particular knowledge of the human being in Kyoto. It certainly did not lead peasants to believe that the Emperor should be actively running the government. The Emperor was where he should be in the grand order of the universe, and the exact details of who he was, where he lived, and what he did exactly weren’t important.
There were, of course, other people, particularly townsfolk, who were more regularly exposed to the existence and importance of the Emperor. During the Edo Period, mourning periods for deceased Emperors were observed in large cities and towns. Businesses sought out the patronage of the Imperial court, then advertised having it to attract customers. The fairly literate commoners of Edo and Osaka read histories and other texts about the Emperor.
And throughout the Edo Period, the common people were increasingly exposed to some of the new ideas about the Emperor’s role that I’ll detail in a second. By the very end of the Edo Period: 1868, the majority of the population still wasn’t caught up in Imperial fervor, but Imperial Loyalism had become a very attractive ideology that appealed to well-to-do peasants and merchants as well as samurai.
Now for the second part of your question: Turning aside from the average citizen, how did the political thinkers and actors of the Tokugawa era think of the relationship between the shogun and Emperor?
Japanese historian Hiroshi Watanabe is the author of A History of Japanese Political Thought, 1600–1901, (translated into English by David Noble). His book traces the evolution of Japanese Confucian thought about government, as well as the rise of anti-Confucian national studies. In his book, among other subjects, he writes about historical views of the shogun’s relationship to the Emperor. Rather than attempt to write a full political history of Japan, I’ll take a brief tour through some of those ideas, with Watanabe as my primary guide. And to save both space and my sanity, I’ve had to pass over a lot of important ideas and people, for which I apologize in advance.
In 1603, Tokugawa Ieyasu, the founder of the Tokugawa dynasty, received the title of shogun from the Emperor of the time. Ieyasu already had taken over Japan. The title was given to him, as it had been to previous shoguns, in recognition of his power.
The Emperor gave Ieyasu the titles "seii tai shōgun" ("barbarian subduing generalissimo") and "naidaijin" "inner minister". In return, the shogun called the emperor "overlord" or "master" (shujō") . Obviously, the confirmation of titles by the emperor had political value, but “People at the time did not interpret them as an official transfer of sovereignty from the emperor to the shogun” (p. 54, Watanabe) (italics mine) for the simple reason that the Emperor of the period did not have any sovereignty to transfer.
There are potential problems here for any decent Confucian scholar. If the Emperor is indeed the "son of heaven", the one who receives "the mandate of heaven", why isn't he in charge? Does the shogun himself independently receive the mandate of heaven, as well as being recognized by the Emperor? Is the shogun just foremost among the vassals of the Emperor? (Tokugawa officials from early on complain that a lot of other lords "incorrectly" believe this.)
One early critical formulation of this relationship came from the scholar Asami Keisai (1652-1711). After asserting that power came from the Emperor, he turned to the question of the shogun's position:
Since [the shogun] reveres the imperial court and respects the orthodox succession, and has received authority over the realm as an imperial representative according to the expressed judgment and will of the emperor, [the shogun] thus stands in proper relationship as a vassal to his sovereign. (-p. 94, Watanabe)
This is a very cagey formulation. Asami is skirting any political trouble by affirming the shogun's authority, but he's still asserting the shogun's authority stems from the Emperor's will. “To say anything further regarding this matter would be inappropriate”, he adds, very diplomatically. Later traditions say that Asami Keisai privately confided in his students that he was hoping for a rebellion against the shogunate and a "restoration" of the Emperor. Whether that's true or not, these stories follow naturally from the ideas he put forward. Scholars like Asami were thinking dangerous thoughts for the shogunate.