The Type 4 Ha-To was conceived as a mobile fire support platform in late 1943, for the 300 mm Type 3 heavy mortar.

The first prototype was completed in late 1944 and taken to the Imperial Japanese Army Academy for testing. Although it was considered as an effective weapon, it was expensive to produce and only three additional units were produced before the surrender of Japan, but none were used in combat.

(Artist's view !)