The Type 4 Ha-To (試製四式重迫撃砲 ハト, Shisei yon-shiki jū-hakugekihō hato) was a self-propelled gun developed by the Imperial Japanese Army for use in World War II.

The Type 4 Ha-To was conceived as a mobile fire support platform in late 1943.

The gun itself weighed close to 1.5 tons, and to keep the center of gravity from shifting and tipping the vehicle over, it could not be elevated more than 50 degrees.

For transportation the barrel was laid horizonal and when set to fire, the rear and baseplate were lowered down to the ground.

[4] The first prototype was completed in late 1944 and taken to the Imperial Japanese Army Academy for testing.