The "Newest" of the Japanese weapons was used on ole "Miss"....the weapon was referred to as the "Kaiten"....translated ["turning of the heavens" or "heaven shaker"]...this 48 ft long weapon....carried 3,418 pounds of high explosives...which was four times the size of the parent torpedo’s successful armament. Launched from the deck of specially adapted I-class mother submarines, single pilots could guide their unwieldy craft towards targets as far as 30 miles away, usually at depths between 15 to 40 feet and at speeds up to 27 knots.
Once released, there was no return.
If you'd care to let your eyes dance over this 6 or so page article on how all this came about...just click: SHIP WRECK and you'll be taken right too the article.
Hope you enjoy!!