The Sen Yu Sho (small supply submarine) were also referred to as the SS Type. These submarines were intended to be mass produced and replace losses of the larger D1/D2 submarines. They featured all welded, modular hulls that allowed for a short five-month construction time. They carried no torpedo tubes, but some could carry ten 18-inch torpedoes as cargo for resupply of midget submarines. They carried a 25-mm AA gun. Twelve boats were laid down of which 10 were completed before the end of the war. Another planned 88 were cancelled.
| Units | 10 |
|---|---|
| Ships | HA-101-109 and HA-111 |
| Year Completed | 1944-1945 |
| Displacement | 429 tons / 493 tons |
| Dimensions | 146 ft x 20 ft x 13.3 ft |
| Machinery | 2 diesels: 400 hp
1 electric motor: 150 hp |
| Speed | 10 knots / 5 knots |
| Range | 4,000 nm @ 8 knots |
| Armament | No TT , 1x25-mm AA mg . |
| Max. Depth | 100 m (330 feet) |
| Crew | 21 officers and men |
