Coalition governments in parliamentary systems become necessary when

Coalition governments in parliamentary systems become necessary when there is no clear majority in Parliament.

Explanation:

A coalition government is a collaboration of ministers and state secretaries from two or more political parties who form a government on the basis of a majority of seats in parliament.

Government coalitions occur in almost all countries where parliamentary representation is elected through the system of proportional representation, whereby none of the participating political parties can rule alone on the basis of a majority vote.

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.