I saw a special on him and he still HATES Americans.....
He alternates between Japan and Brazil because Japan wouldn't tolerate his hatred and he couldn't tolerate their feelings about the war. That was kind of the core of the matter, so he goes back and forth...
I saw this last year sometime and was completely surprised as to his feelings today.....
Unfortunately, some soldiers cannot let go, even after many years have passed. After the war ended, some of the WWII Japanese veterans have become good friends with the U.S. & Allied veterans, while some have not.
A good example of this is one of the Japanese pilots who led the first wave on the attack on Pearl Harbor, Mitsuo Fuchida. After the war ended, Fuchida became greatly disillusioned with his government after the war ended. He converted to Christianity, and became a missionary pastor. He also had obtained a green card, and resided for a time in the United States. (Fuchida passed away from diabetic complications in Kashiwara, near Osaka on May 30, 1976 at the age of 73.)
Keep in mind also that in Hiroo Onoda's mind, he was still "fighting" against the Americans some 29 years after the war had ended. (He had numerous skirmishes with the Philippine police during his 29 years in the Lubang jungle, and some of the men under his command were killed.) He also did not have time to adjust, when Japan went through the post-war period. (Especially, when the Americans occupied Japan, and made sweeping reforms in the Japanese government.)
The Japan that Onoda had left during WWII, was radically different from the Japan that he had returned to in 1974. In many ways, his mentality was still stuck in prewar & WWII Japan. (Girls wearing miniskirts & Go Go boots & loud disco music proved to be too much for him to adjust.)
If you drop a man off from the 1940's suddenly into our present world, it's very likely that he would have quite a difficult time to adjust in our time. (Shades of Captain America!)
The interesting thing about it is that there were actually several Japanese Imperial Army officers & Imperial Naval officers who thought that it was a mistake to fight the Americans. Many of them believed that they should have fought the Russians & the communists instead. However, they had to put their feelings aside, because they believed that the wishes of their government should come first.
Admiral Isoroku Yamamoto, (Who planned the attack on Pearl Harbor) also opposed the war with America, and he thought that it was also a big mistake. He had made many friends in America when he studied at Harvard University in America, and spoke English quite fluently. He also opposed Japan's invasion of China, and was greatly opposed to Japan joining the 1940 Tripartite Pact with Nazi Germany. (He felt strongly that the Nazis could not be trusted, and Adolph Hitler would turn on Japan eventually.) However, out of duty to his country, and to his Emperor, he had to put those feelings aside when he was asked to fight.
It's the same with the WWII veterans of the German military. Some have become good friends with the WWII American & Allied forces after the war have ended, while some have not.
But irregardless of Hiroo Sonoda's feelings, he is still on the record books as the 2nd to the last Axis soldier to surrender.
However, although there were unconfirmed accounts that there were Japanese soldiers still hiding in the various jungles of the South Pacific & Southeast Asia, long after Hiroo Sonoda and Teruo Nakamura had surrendered. (There were unconfirmed sightings & rumours as late as 1997.) Whether that is true or not, it may remain as one of the great mystery of our times.