The Type 1 Ho-Ni I was the first self-propelled gun design of this particular type. They were meant to be
self-propelled artillery and tank destroyers for
armored divisions. The plan was for the Type 1 Ho-Ni I gun tank to form part of a fire support company in each of the tank regiments. The first conversion took place in June, 1941. The production model that followed had a larger fighting compartment due to enlarged side armor plates. Further, the periscope and rangefinder were removed and the gun mantlet was revised. Production of the Type 1 Ho-Ni I took place during 1942. Only a total of 26 Type 1 Ho-Ni I units were produced. The Type 1 Ho-Ni I was developed by using the existing
Type 97 chassis and engine, and replacing the
gun turret with a
Type 90 75 mm field gun mounted in an open
casemate with frontal and side armour only. The gun could elevate from -5 to +25 degrees; the gun mounting could also traverse up to 20 degrees either side, so the entire vehicle did not have to be turned. The Type 1 Ho-Ni I carried 54 rounds of ammunition. They were designed to operate as self-propelled artillery at ranges of up to . The design had no provision for a defensive
machine gun, which together with the open structure made it vulnerable in close combat. The Type 97 chassis,
suspension and
diesel engine were used unchanged. The Type 90 75 mm field gun was protected on three sides by 51 mm thick armored plate. The hull armored plate was 25 mm on the sides and 20 mm on the rear. ==Variants==