How was Japan treated by the Treaty of Versailles?
The Japanese did not feel they were not treated as fully equals in the Treaty of Versailles.
Japan actually was well rewarded by the Treaty of Versailles.
The German colonies and territories in the Pacific were given to Japan. The Marianas, the Carolinas, and Marshall island groups were given to Japan. These island groups would become major Japanese strongholds in World War II.
Also the German concessions in China in Shandong were given to Japanese control, giving Japan a major foothold in China.
Japan wanted to be given complete control of China. Japan felt that the Treaty of Versailles failed to endorse the principle of equality of all races. Japan had not fought in World War I. The French, and British did not treat the Japanese as equal partners, as Japan wanted. If these unequal treatments were due to racism or based on on unequal participation in war.