As the self-appointed, arbitrary judge of Japanese cultural awareness (JCA), you get more because you didn’t mention Rising Sun. As much as I enjoyed the Torantino classic I am mystified as to why you watch it twice a week.
When discussing this, we have to remember that nothing which will come out of the Japan’s Imperial Household Agency is likely to ever give an accurate picture of Hirohito, so scholars are limited to reading between the lines. One problem with taking individual quotes is that if WWII were limited to 18 snapshots, how well could the war be portrayed? Likewise, releasing carefully selected documents will likely not give an accurate portrait of the complexity of Hirohito’s involvement, even at 81 volumes. I donno, maybe they will be refreshingly honest, but I wouldn’t bet the ranch on it.
The question of who was in charge in 1937 to '45 in Japan cannot be answered because no one was in charge. It was in someways like an unofficial version of the checks and balances of the US constitution, but all done by informal rules and not by clearly delineated responsibilities.
Some of the key players:
By far, the driving force was the IJA, and specifically the ultra nationalistic factions. Note the plural, they didn’t all speak with one voice. Field generals were making decisions first and informing HQ later. Not little decisions, but things such as setting up the http://en.wikipedia.org/wiki/Mukden_IncidentMukden Incident, which lead to the invasion of Manchuria and Marco Polo Bridge Incident which lead to direct war with China.
The fear that a local commander could take steps which would drag the West into war was real, as can be seen in the warning message to Washington by the US Ambassador to Japan in early 1941.
The IJA generals were crazy, at one time some were thinking they could attack Russia at the same time they were fighting the Allies. They were also woefully uninformed about anything outside of Japan.
The PM and other important leaders were from the military. The Meiji constitution and later rules make it that such that both the Ministers of War (Army) Navy had to be active duty flag officers, as well as not reporting to the PM. They were in the cabinet but (nominally) reported directly to the emperor. The position of Minister of War was in reality more powerful that that of the PM. Tojo was a powerful PM because he simultaneously held the more powerful position of the Minister of War
Either one of these military ministers could cause a government to fall simply by resigning and for the branch of the service to not allow one of the flag officers to become a replacement. This was a real concern at times, especially at the end of the war.
Were I an historian looking for an interesting topic to research, my first pick would be the end of the war when they were discussing surrendering or not, why didn’t General Anami, the Minister of War and the most powerful person in Japan leave the conference room in the bunker beneath the Imperial Palace to take a piss and keep on walking out the door? The government would fail; Hirohito would be unable to name a successor to the toothless prime minister, Admiral Suzuki (ret); and the IJA would declare martial law. Hirohito could either agree to support them or be replaced by one of his hard-core relatives.
Japanese ultra rightists had become increasingly violent and intimidating in the years leading up to the war. Even Admiral Yamamoto needed to go into hiding at one point to escape possible assassination.
Most of the IJN was less fanatical and more people who were more realistic about the industrial power of the West. However, many leaders were wanting part of the action when the IJA was carving up China.
Civilian politicians. What civilians? The Minister of Foreign Affairs would be a civilian, and some of the lesser cabinet members, but none of the other key players.
The backroom dealers. The elder statesmen had been give a certain degree of influence during the Meiji period although that was waning and by the war would be much less.
Hirohito. Westerns used to the concept of an all-powerful God do not understand how the emperor could be considered divine, but without actual power, which is the situation for most of Japanese history. The Meiji Restoration had placed the emperor in a position of some political power. Even so, there were real limits and not much actual power.
Emperor Meiji died in 1912 when Hirohito was 11. Hirohito’s father became the next emperor, but suffered from mental illness and Hirohito was named as regent at age 20, forcing him to learn on-the-job with no real role model.
Around the emperor would be Lord Keeper of the Privy Seal, with a lot of the functions of a chief of staff including limiting access to the emperor; the Household Agency and other advisers.
It would probably take someone with far greater skill to have significantly changed events, and it’s likely that Hirohito didn’t have that skill.
Leading up to the war, Roosevelt critically underestimated Japanese will and abilities; completely misjudging their response. The US Secretaries of State and Navy opposed several of the key measures taken in the fateful summer of 1945 because the US wasn’t prepared for war, and they understood that the sanctions put Japan into a position where they would feel that they had choice but to go to war.
So, to answer your question. We really don’t know and I don’t believe that the further releases will really answer the question. I hope to be proved wrong, though, but doubt it.