Only two prototypes were completed before the end of the war. Used a five-cylinder swashplate engine.

An older type still in service ten years after service introduction. "Nell" (G3M) torpedo bombers used this weapon against HMS Prince of Wales and HMS Repulse on 10 December 1941.

Compared to Mod 1, Mod 2 had a heavier explosive charge, a thinner air vessel and anti-roll stabilizers. It was first delivered in April 1941 and was carried into action by "Betty" (G4M) bombers against the Prince of Wales and Repulse. A version of this torpedo was heavily modified for use in shallow waters and was carried by "Kate" (B5N) attack planes at Pearl Harbor.

Compared to Mod 2, Mod 3 had a heavier explosive charge, the air vessel was thickened for a heavier charge. Bronze parts were substituted for steel where possible and eight tail fins were experimented with in some units.

A limited number of these torpedoes were made but they do not appear to have entered service use. Powered by a dual-row, eight cylinder radial engine with poppet valves.

Designed for Midget Submarines and was essentially a smaller version of the Type 93 and Type 95 torpedoes. Only about 100 were made as similar problems with the first air vessel were found. Used operationally only during the Pearl Harbor attack. Many were reworked to become "Specials" as described in the next section.

Designed for Midget Submarines. Also known as the Type 97 Special. Worked on air enriched to 38% oxygen and bore the same relationship to the Type 97 as did the Type 96 did to the Type 95. Called the Type 98 to fill a gap in the series, a total of about 130 were produced. Used operationally during the attack at Sydney, Australia, on 31 May 1942.

A modification of the aerial Type 91 Mod 3 with a larger air vessel and a different read buoyancy chamber. Engine was an dual-row, eight-cylinder radial. About 800 were made between 1943 and 1945. In addition, there was a Type 2 Special of which about 100 were manufactured in 1944. This had the same explosive charge but the smaller air vessel of the Type 91.

A further modification of the Type 91 Mod 3 Strong. This version was strengthened to permit a launch speed of 400 knots. The design was greatly simplified for easier production including the replacement of many steel parts by bronze.

Also note that the designation system for modifications changed from "Mod" to "Mark" with this torpedo.

Similar to the previous Type 4 Mod 2 with a larger warhead. Later versions had a more pointed head, as noted for the earlier Models. This gave an extra two knots in speed, as shown in the table above.

The design of this torpedo was inspired by the German Navy's successful one of World War I. Work started in 1921 and in 1925 workable models were produced. Design work continued and the Type 92 Mod 1 was ready for production in 1934. As there was no need for this torpedo at that time, the design was set aside.

In 1942 production started to supplement the Type 95 torpedoes. The Type 92 was slower than the Type 95 but had even less track and was easier to produce. The Type 92 Mod 2 was to have been based upon the German G7e and ten of these torpedoes were delivered to Japan in 1942. However, a lack of manpower killed this project.

Homing gear based upon the comparison of sound intensity was studied for this torpedo, but it appears that the torpedo itself was too noisy for this to be successful.

Model 1 was an experimental aircraft torpedo using a kerosene, oxygen and sea water propulsion mixture that was apparently never made. Reliable details are lacking.

A smaller version of the Type 93 developed for submarines. As per the Type 93, later versions had a more pointed head, giving a similar two knot increase in speed, as shown in the table above.

A slightly improved version, trading a shorter range for a much larger explosive charge. As per the Type 93, later versions had a more pointed head, giving a similar two knot increase in speed, as shown in the table above.

This was a modified Type 95 Mod 1 torpedo developed because of troubles with the "first air vessel" in the former. Type 96 used 36% oxygen rather than pure oxygen to reduce starting problems. This also allowed a thin coating of lubricating oil to be used on valves where as with pure oxygen they had to be completely oil free which caused corrosion and irregular functioning. The title of "Type 96" seems to have been given to fill a gap in the series. As per the Type 93, later versions had a more pointed head, giving a similar two knot increase in speed, as shown in the table above.

Model 2 was an experimental type designed in 1935 to meet a staff requirement for a higher speed torpedo for destroyers. Only two were built and experiments were discontinued until 1941. In that year, two new engine designs were produced, both essentially modifications of the two-cylinder double-acting Whitehead type.

In the first engine, the cylinder bore was increased and the prototype with this engine achieved speeds of 51 knots. The second engine had thicker cylinder walls and heads and stronger piston rods. This engine developed pressures of 650 lbs./in² (45 kg/cm²) and 850 HP.

The head of the torpedo was made to a finer, more streamlined design based upon Italian torpedoes, as noted above. The propeller pitch was reduced and the RPMs increased. This prototype made three runs at 56 knots over a 5,500 yard (5,000 m) course.

This design was not further pursued and did not enter service.

A slightly improved version, trading a shorter range for a much larger explosive charge. The first air vessel was replaced by carbon tetrachloride to prevent an explosion on ignition. Earlier versions of these torpedoes may be distinguished by their round-nosed heads. Later versions had a more pointed head, as noted for the earlier Models. This gave an extra two knots in speed, as shown in the table above.

Experimental Turbine powered torpedo. Turbine speed was 17,500 rpm geared down to 1,650 rpm at the propellers. It was found to be difficult to keep this torpedo from breaking surface during its runs and development was halted prior to the start of the Pacific War.