I think you (and many others) misunderstand the authority of Japanese Emperor over the government. Even before 1945 Surrender, a Japanese Emperor don't have the same power as Russian Tsar, German Kaiser, or Chinese Emperor. His rule are very indirect, arguably even more indirect than contemporary constitutional monarch like the British King.
Meiji constitution is among the most vague constitution ever written. It work as long the people who wrote it still in power (which are the genro) and the Emperor who reign have the strength and subtlety to control those who called the shots in the government. Emperor Meiji prove to be excelent for this task, but mentally-handicapped Mutsuhito and weak-willed Hirohito fail to do it.
If Hirohito try half-assedly restrain those who commit the Mukden Incident (or the Marco Polo incident, or Nomonhan Incident, or... the list quite long) and defuse the situation, there will be coup. Then they will simply declare the Emperor have been "misguided by corrupt and evil advisor", after that he will be sidelined from the decision making (not that he make any decision in the first place).
Except the OP never stated that the emperor should be Hirohito. nor would even the people would be even in power to do such a thing. The only requirement is for Japan not to invade of China which could make many different things assuming different PoD.
All your assumption is based on OTL even with the success of a coup. That means in order for you assumptions to be true everything must happen according to otl. From successful, same people in power, etc.
However, if the op required it to be pod 1935, then I would agree would you since all your assumtions already happened.