In 1942, the Ministry of War and the Ministry of Commerce and Industry requested the Automotive Engineering Committee of the Ministry of Commerce and Industry to work on the specifications of Japanese-made high-end vehicles.
The Committee ordered three companies, including Isuzu’s predecessor Diesel Automobile Industries Co., Ltd., to submit specifications. After screening, the Ministry of Commerce and Industry instructed Diesel Automobile to make two prototype vehicles by June the following year.

It was considered very difficult to make a prototype in six months since Diesel Automobile did not manufacture passenger vehicles at the time. However, through the all-out company-wide efforts, the prototype vehicles were completed in September 1943.

Torsion bar independent suspension was used for the front axle. The prototype vehicles were fuel efficient and comfortable, and obtained a high score on the road tests.