The start might have been in the Meiji era, when the were looking for an inspiration for a constitution they looked at the UK and Germany/Prussia. They did not chose the UK. As well in their government the minister of the Navy and Army had to be approved by the Navy and Army, change it so the minister is a civilian and could help. As well, the first time there is a group of young officers that try a coup, after it fails have the Emperor say something like,"No true Japanese citizen would do anything like that." Have them stripped of their standing in the community. As well have when a minister retires, they have little to no say in the current government. If WW1 happens like normal, send the 'gunho' troops to the Western Front and allow them the 'honour' of going over the top.