Captain Osaki was a member of the Imperial Japanese Army during World War II. In March of 1944, he and some of his men appeared outside of American waters aboard a Japanese aircraft carrier. Smuggling himself onto the mainland, he and his men captured an American bomber that just so happened to have the Young Allies on board for a joyride. Osaki and his men took the Young Allies hostage and flew the plane back to the Japanese aircraft carrier. Along the way, Osaki explained that he intended to use the American bomber to stage bombing in the United States, believing that flying an American bomber would throw off the authorities.
The Young Allies were locked up in the prisoner hold until Osaki and his men were ready to launch their first attack. Osaki then had the Young Allies taken from their cell in order to force them to witness his attack. When the Young Allies attempted to break free, Osaki and his men subdued the youths again and then tied them to the bombs to eliminate them as well when the bombs were dropped.
The Young Allies were able to free themselves and overpower Osaki and his men, retaking control of the plane. They then turned the craft around, planning to bomb the Japanese ship. Despite Osaki's attempt to warn his comrades, the Young Allies dropped the bombs. When Osaki attempted to attack Toro, the young man landed a solid punch that sent Osaki falling out of the plane with the bombs, and he was killed in the subsequent explosion that also sank his ship.
Osaki used a machine gun.