This is a key aspect of a unitary system of government

In a unitary state, the central government may grant some powers to its local governments through a legislative process called “devolution.” However, the central government reserves supreme power and can revoke the powers it devolves to the local governments or invalidate their actions.

explanation:

japan participated in world war i from 1914 to 1918 in an alliance with entente powers and played an important role in securing the sea lanes in the west pacific and indian oceans against the imperial german navy as the member of the allies.