[2] Later that month, the IJA′s 10th Army Staff Headquarters, which was responsible for all IJA-operated ships, decided it would need to develop its own transport submarine — which it provisionally designated "transport boat" (Yuso-tei, abbreviated as Yu-tei) — with which to supply isolated IJA island garrisons in the Pacific Ocean.

[2] The IJA staff established a requirement for a submarine capable of at least 5 knots (9.3 km/h; 5.8 mph) on the surface and a cargo capacity of 24 tons of rice.

[2] It selected Hitachi′s Kasado Works in Kudamatsu, Japan, to build the prototype, Yu 1, and the first production series.

[2] When almost complete, the submarine was launched by simply moving the cradles into the water, after which final fitting-out took place.

[3]) Each manufacturer's submarines differed in detail from those built by other companies, resulting in four unofficial subclasses of the Yu I type.

An improved IJA transport submarine designated the Yu II type was planned, but the prototype for it was not completed.

[3][5] When the war ended in August 1945, the IJA was preparing to initiate a submarine supply route between Senzaki in Yamaguchi Prefecture and Pusan, Korea.

They were longer and had a slightly higher displacement than the Yu 1 subclass and a more powerful diesel engine which increased their maximum surface speed by about 2 knots (3.7 km/h; 2.3 mph).

The Yu 2001 subclass featured a "repose room"[3] — a deckhouse built aft from the root of the conning tower — for improved crew comfort.