This was the Navy Yokosho 2-Go Reconnaissance seaplane; single-engine, twin-float, submarine-borne reconnaissance seaplane. It had detachable wings and floats for submarine stowage and was an open cockpit plane.

130-150 hp Mitsubishi built MONGOOSE five cylinder air-cooled engine (Yokosho-2)
130-160 hp Gasuden JIMPU seven cylinder air-cooled radial engine (Type-91)
Both driving wooden propeller.
Wingspan was 8 meters (26 feet 3 inches)
Length was 6.69 meters (21 feet 11.5 inches)
Height was 2.87 meters (9 feet 5 inches)
Weight (empty) was 570 kg (1,254 pounds)
Weight (loaded) was 750 KG (1,650 pounds)
Maximum speed was 91 knots
Rate of climb to 3,000m (9,843 feet) was 20 minutes 14 seconds
Endurance was 4.4 hours.

After the end of the Naval Holiday - the expiry of Washington and London Treaties - I.J.N. launched a five-year plan (1937-1941) of naval build-up. This plan was top-secret, and its content was not revealed even to the National Diet (Parliament) that passed the naval budget. It included the super-battleships YAMATO and MUSASHI, the largest warships ever built, armed with 46cm (18.1 inch) guns. As far as submarines were concerned, thirteen new type submarines were to be built. No longer restricted by the arms limitation treaties, these submarines were designed freely to give them optimum performance.

As we have seen, up to this time, there had been two distinctly different series of I-Boats: the JUNSEN with long endurance but with comparatively slow surface speed used primarily for long-range reconnaissance and secondarily commerce-raiding; and the KAIDAI with high surface speed designed to take part in fleet actions. But now, as a result of the advent of the superior KAMPON diesel powerplant, a submarine with long radius of operation as well as high surface speed could be designed. Basically three kinds of new type submarines were designed and built. They were the A-TYPE (KO-GATA) and the B-TYPE (OTSU-GATA) and the C-TYPE (HEI-GATA). These three types had several sub-types, and they will be described in details later, but here their general characteristics will be explained briefly.

The A-Type would be a headquarters or command submarine with Flagship facilities which would include additional communications facilities and space for staff. There would be assigned one A-Type to each submarine squadron which would consist of three submarine divisions which, in turn, would be formed with three squadrons each. The A-Type would be equipped with one float plane, a single hangar and a catapult on the foredeck. It was generally similar to the JUNSEN Type 3 but was larger, with the surface displacement of nearly 2,500 tons.