The Imperial Japanese Army (IJA) developed the Type 89 Chi-Ro tank to address the Type 87 Chi-I’s shortcomings in weight and speed, using lighter and stronger steel armor, and equipping it with a Type 90 57 mm gun and two Type 91 6.5 mm machine guns. First mass-produced in Japan in 1931, the Type 89 had two variants: the Kō with a water-cooled gasoline engine, and the Otsu featuring an air-cooled diesel engine and enhanced frontal armor. Over its production run, 113 Kō and 291 Otsu tanks were built. The Type 89 saw its initial combat in the First Battle of Shanghai in 1932 and continued service through the Second Sino-Japanese War starting in 1937. However, it soon became obsolete, leading to the development and subsequent adoption of the Mitsubishi "Chi-Ha" Type 97 medium tank as its replacement.