The Mitsubishi Heavy Industries/Japan Steel Works Type 99 155 mm self-propelled howitzer is a self-propelled howitzer of the Japanese Ground Self-Defense Force, which was developed as successor of the Type 75 155 mm Self-propelled howitzer. Research and development was started from 1985 as a successor for the older Type 75 self-propelled 155 mm howitzer. Japan Steel Works was the primary contractor, and developed the main gun and the turret. The Type 99 uses a modified chassis from the Mitsubish