My Mapping Projects

How could I interpret the map's color?

In February 1945, Vietnam, Laos, and Cambodia had the same color. Understandable. They're still parts of French Indochina. But I don't think France has control over parts of Indonesia and China.
Why does China have many colors? There's only one sovereign state at that time, the Republic of China.
How about the Empire of Japan? They'd already occupied a lot of land at that time, but the map shows only the current day Korea and Japan have the same color.

I'm not good at history, so my observations above may be incorrect.