This isn't in the FAQ but comes up rather frequently. Just searching the subreddit for "Hirohito" will bring up several answers.

The short answer is basically "It's complicated."

A good place to start is this multi-part answer from u/starwarsnerd222 which seems to be an expansion of an earlier answer to a similar question here.

This older answer from u/catfulu is also useful. This even older answer from u/thewinstore also provides some information, though it focuses more on the decision to keep Hirohito in power.

Several answers also link to many other answers, like this and this from u/jbdyer, and this from u/someanonymous.

You may yet get an answer to your question here, but that should give you a start. You can find other answers searching through the subreddit.