Japan in the run up to WW2 is about as close to a military run state as the East has seen.

Simply put there were two parties running the nation. The Imperial Army and Imperial Navy. Civilian parties and legislative acts were essentially secondary in nature and any voice that did not toe the militaristic Imperial line were drowned out.

The movement was most strongly felt in the mid ranking officers who had grown up under it, and who saw themselves as carrying on long standing Samurai traditions.

In fact no less a figure as Yamamoto himself received death threats from groups because he advocated for the adoption of the Washington Naval treaty, which in circle was seen as a slap in the face to the nation and evidence of a desire on the part of Britain and the US of subjugating Japan to second tier status.

The Navy in particular saw rightly or wrongly that they needed direct control of sources of precious resources like Rubber and Oil as crucial to further expand their Empire and they saw this lien of thought to be confirmed when FDR began progressively stronger trade limitations in response to the Army's war in China. And they did not believe they could expand south to secure the sources in the Dutch East Indies and Indonesia without coming into conflict with the US. Therefore the question quickly shifted from "if Japan should fight the US" to "How could Japan even win against the US" and went from there.

Would recommend as a good coverage of the run up to was as Hornfisher's Pacific Crucible, the first part of his on going 3 part series about the war.