Type 89 I-Go medium tank Type 91 6.5 mm machine guns. One was located in the front hull and the other placed in a turret ball mount pointed towards the rear, a practice followed with most Japanese tanks. The Type 90 57 mm tank gun had a barrel length of (L14.9) el angle of fire of −15 to +20 degrees, AZ angle of fire of 20 degrees, muzzle velocity of , and could penetrate of 20 mm of armor at 500 m (0.8 in/550 yd). Rather than using soft iron armor, as on the earlier Chi-I, the designers chose to use steel plate armor developed
Type 90 Kyū-maru leading to higher per unit costs than comparable models from NATO countries such as the M1 Abrams and the Challenger 2. Development of upgrades to the Type 90 suffered both as a result of limited budget, which caused procurement delays, and funding prioritization in favor of the Type 10 Main Battle Tank. Due to a perception that Type 90s are unsuited to operations in the tight confines of Japan's urban areas, they are preferentially assigned to the JGSDF Fuji School Brigade and the 7th Armored Division based in Hokkaido, where there is sufficient room for maneuver. With the exception of