From the article:
The Type 97 Chi-Ha was developed as a replacement for the Type 89 Chi-Ro which was considered obsolete by the late 1930s. In essence, the Type 97 was simply a scaled-up version of the Type 95 Ha-Go but with greater power-to-weight ratio, thicker armour and a two-man turret.
Armed with a short-barrelled 57mm main gun, the primary role of the Type 97 was infantry support to which the gun was well suited. Secondary armament consisted of two 7.7mm machine-guns, one mounted in the front of the hull and the other in the rear of the turret.
After facing off again the Soviet BT-5 and BT-7 tanks armed with their 45mm guns, it soon became that the 57mm gun had limited value against opposing tanks. This led to the development of the Type 1 47mm gun; a direct competitor to the Soviet 45mm gun. An up-gunned version of the Type 97 designated the Type 97-Kai Shinhoto Chi-Ha and went in production in 1942.