The first cars, known as the PH10 series, were based on the Mk VI Hillman Minx. These had a 1265 cc sidevalve engine (37.5 horsepower), 4 speed manual transmission with column shift and drum brakes. Seating capacity was 4 people. They were assembled almost entirely from parts imported from the UK. There was only 6% local content; tyres and batteries were sourced in Japan and the assembled cars were also painted in the Isuzu factory. The first PH10s went on sale in November 1953 through the Yamato Motor Company, which was jointly owned by Rootes and Isuzu.
The PH11 series went on sale in August 1954 and was based on the Mark VII Hillman Minx, and was very similar in appearance to the previous model, the only differences being longer rear wings and bigger boot (trunk). They were mechanically similar to the PH10. As can be seen from this scan of a Japanese brochure the Californian Hardtop model was apparently offered for sale in Japan, but it's not known how many were sold. Estates and Convertibles were also shown in the brochure, but only the sedan was built in Japan. By the time of the PH 11, the car had about 18% local content.
The PH12 model was based on the Hillman Minx MkVIII, and went on sale in February 1955. The body was similar to the PH11, but the grille now had vertical bars with a single horizontal bar across the centre. The big news for the PH12 was the new 1390 cc overhead valve motor with 43 horsepower, which pushed the top speed to over 70 miles per hour. During the PH12 model run, two tone paint with extra chrome trim was introduced, this style being called the "Gay Look". The PH12 saw local content rise from 19% in March 1955 to 37% in May 1956.