It depends what you mean by major. Japan was significant, but certainly not one of the main actors such as France or the UK. Japan did take an important German colony at Qingdao after a successful siege, as well as Germany's Pacific colonies. She also aided in suppressing a rebellion in Singapore and performed escort duties for troop convoys in the latter half of the war. In addition to these military actions, Japan also exported large amounts of material to the Allies (Exports quadrupled 1913-1918)