You're right that these are the sorts of figures that influenced the decision. It's also worth remembering that there were high-ranking members of the Japanese military who questioned the logic of the war or ordered retreats from indefensible positions, but were often arrested, assassinated, or ordered to commit suicide. Any stance other than loud, defiant resistance proved dangerous within a military hierarchy dominated by extremists.

There is also some evidence that Japanese Army officers created a deliberate culture of extreme violence, ordering ordinary soldiers to commit atrocities, for example, as a way of ruling out surrender as an option. The soldiers would then assume that their treatment by the other side would be identical.

I don't object to the word "fanatic" out of some semantic pedantry or because it's derogatory per se, but I think it robs us of some consideration of the individuals in question, and the various strands of policy, training, propaganda, fear, group pressure, and nostalgic death-worshipping cultural narratives to which they were subjected. The result was certainly the perception of fanaticism, which was intended to demoralize the Allies but backfired terribly, like the decision to prosecute the war itself. (And, as you point out, produced an enormous wastage of lives for no real gain.)