Compatibility summary
Your Japan plug may fit in China outlets, as both use at least one common plug type. Voltage differs by more than 20% — a voltage converter may be needed for some appliances.
Plug comparison
Japan plug types: A B
China plug types: A C I
Both countries share at least one plug type (A B and A C I), so some plugs may work without an adapter. Check your appliance.
Voltage comparison
Japan: 100V, 50Hz
China: 220V, 50Hz
Voltage converter recommended (Japan 100V vs China 220V).