The frame was made out of duralumin used in airplanes.
In 1947, a mere two year after the end of World War II, an airplane design engineer who had been designing the Isshiki Rikko at the former Mitsubishi Heavy Industries' Tsu Factory, produced the Jujigo, a bicycle with a duralumin frame. Using 2 mm-thick duralumin that was no longer needed for building planes, he came up with an innovative bicycle design crossing two rivet-fastened box structure frames which were widely used by ship builders at the time. The first model was based on an everyday bicycle from Great Britain, but from the second model on, they started basing the Jujigo on sports bicycles, and it continued to be produced up to a fourth model. The Jujigo was also ridden in the bike races of the period and it attracted much attention.