Japan Steel Works
The development of Type 99 self-propelled howitzer began in 1985 in order to replace the old Type 75 self-propelled howitzer. The new self-propelled artillery would use a L52 155 mm gun instead of the old L30 155 mm gun and would also mount the latest Fire-control system. Mitsubishi Heavy Industries was tasked to design the chassis and the gun would be manufactured by Japan Steel Works.