I agree that the best solution would be to jail the entire royal family, or at the very least Remmile and the Emperor, but if the group does that, the public would probably revolt. There are in fact some parallels with Japan's own last Emperor after WWII, Hirohito was also kept as a figure head IIRC. Heck, the whole thing parallels the conflict between Japan and America, it started with an unexpected attack to a port, where civilians where harmed. The wounded nation retaliated, and then the ones who attacked first ended up defeated. There are of course several differences, but I wonder if the author did that deliveredly.