Japan Steel Works
An emergency project was initiated in December 1943, to address this issue. To save time, the existing Type 3 design was scaled up to 15 centimeters in caliber, with a corresponding increase in range and firepower. The project was completed relatively quickly, with test guns ready for firing 17 months after the project starting. However, by this point it was already too late — all major Japanese cities had been destroyed by the strategic bombing campaign against Japan, and American bombers were moving onto secondary targets. Japan lacked the raw materials and industrial infrastructure to follow through with mass production. Only two units of the powerful new Type 5 were completed before the surrender of Japan. One unit each was produced by the Army’s Osaka Arsenal and by Japan Steel Works.