The Kairyu was based on the Type A midget. Kairyu were equipped with small diving planes fitted amidships. They were somewhat smaller than the Type A midgets. The first Kairyu was begun in 1943 and production commenced in February 1945. By war's end, 215 were completed, and another 207 were under construction. Kairyu were deployed for home island defense in concealed bases in Kyushu and Shikoku, but as one result of the atomic bombing, none saw action.
At least three Kairyu survived the war and are on display at:
- Japanese Maritime Self-Defence Service School, Eta Jima, Japan.
- Yamato Museum, Kure City, Japan.
- U.S. Navy Nautilus Submarine Force Library and Museum, Groton, Connecticut.
| Units | 760 planned |
|---|---|
| Years Completed | 1944-1945 |
| Displacement | 19.2 tons submerged |
| Dimensions | 55.5 ft x 4.5 ft |
| Machinery | 1 gasoline engine: 85
hp
1 electric motor: 80 hp |
| Speed | 7.5 knots / 10 knots |
| Range | 450 nm @ 5 knots surfaced/36 nm @ 3 knots submerged |
| Armament | 2x457mm (17.7-inch) TT fwd + (2 torpedoes) or a 1,320-lb warhead without torpedoes. |
| Max. Depth | 100 m (330 feet with torpedoes) |
| Crew | 2 |
