I just read this autobiography of Hiroo Onoda, a Japanese soldier sent to the Philippines in 1944, and ranking officer in a group of soldiers who didn't believe the war really ended in 1945. He didn't surrender till 1974. The Wikipedia article about him gives a nice summary of his story. I heard about him a few years ago, on Slashdot, I think, but never followed up on it till now. I finally read his book, and it is simply amazing.
It's a fairly quick read, but very engaging, and he gives enough background and explains what they were thinking, so it starts to make sense that they thought the war had not ended. He doesn't ignore the many bad parts about his time on the island, but there's not much self-pity either. He and his fellow soldiers thought they were fighting in a very long-running war, with guerrilla tactics, and evidence to the contrary was thought to be an elaborate enemy trick.
His experience raises some good questions about how you can find the truth behind the information you receive, especially when you consider that superior officers could be captured and forced to give bad orders, or passwords can be intercepted by the enemy.
There were other famous Japanese holdouts after the end of World War II, but Hiroo Onoda seems to have become and stayed a real war hero in Japan, more than any of the others. I was surprised to learn that two more "lost" Japanese soldiers surfaced this year, in Russia and the Ukraine.
Anyway, very interesting how life turns out for some people, and amazing what they make of strange and tough circumstances.