Your question is missing information, but I'll try to help what I can.
The main dictators of WWII were:
Adolf Hitler of Germany (and the Nazi party)
Benito Mussolini of Italy
Hirohito of Japan
These were all members of the Axis powers.
If those 3 are your answer choices, your answer would be Hirohito.
Hirohito was the emperor, yes. But, Hideki Tojo had a bigger hand in the totalitarian side of Japan. He was the one established as the totalitarian dictator of Japan.
If these don't help, please give the multiple choice answers that go with the question- since by the way it's worded, it shows that it is in fact a multiple choice question.
Hope this helps you!