Inspired by German self-propelled guns the Type 4 Ho-Ro assault gun was based on a reinforced Type 97 Chi-Ha tank chassis. The Type 4 Ho-Ro mounted the Type 38 150mm howitzer. Surrounding the front of the howitzer was 25mm of armour plating the open rear leaving the crew susceptible to close combat and shrapnel.
The 150mm gun predominantly fired Type 88 APHE (armour-piercing high explosive) rounds although it could also fire HEAT (high explosive anti-tank) shells. Ammunition was stored in a container on the rear engine deck.
Rushed into service towards the end of World War II, the Ho-Ro was deployed in batteries of four vehicles. It saw action during the Philippines Campaign and during the American assault on Okinawa where it was heavily outnumbered by US artillery assets.