ノモンハン事件
After the Battles of Khalkhin Gol against the Soviet Union in 1939, Japan tried to improve their tank designs using lessons learned from this battle. Many Japanese tanks such as the Type 95 Ha-Go light tank and the Type 97 Chi-Ha medium tanks were proven to be insufficient to counter Soviet armored forces. A larger tank design was urgently needed. A super heavy tank project was proposed directly in response to the Japanese defeat at Khalkhin Gol.