 Previous gun tanks, Type 1 Ho-Ni I and Type 2 Ho-I, were not really optimized designs.Type 1 Ho-Ni I used an open casemate with frontal and side armour only for the main gun, which made the crew vulnerable in close combat situations.The Type 2 Ho-I, despite its enclosed rotating turret, was armed with a low-velocity howitzer more suitable against gun emplacements and fortifications and required specialized shaped-charge warhead ammunition in tank destroyer roles.