In World II Japan developed a suicide torpedo (Kaiten)

The very first model was nothing much more than a Type 93 torpedo engine compartment attached to a cylinder that would become the pilot's compartment with trimming ballast in place of the warhead and other electronics and hydraulics. The torpedo's pneumatic gyroscope was replaced by an electric model and controls were linked up to give the pilot full control of the weapon.

The original designers and testers of this new weapon were Lieutenant Hiroshi Kuroki and Lieutenant Sekio Nishina. They were both to die at the controls of Kaitens, Lieutenant Kuroki in a very early training prototype.

In total six models of Kaiten were designed, Types 1, 2, 4, 5 and 6 being based on the Type 93 torpedo. The Type 10 was the only model based on the Type 92 torpedo.

Early designs allowed the pilot to escape after the final acceleration toward the target. There is no record of any pilot attempting to escape or intending to do so, and this provision was dropped from later Kaitens, so that, once inside, the pilot could not unlock the hatches. The Kaiten was fitted with a self-destruct control, intended for use if an attack failed or the impact fuse failed.