Did Japan practice communism during WW2? ?

The Japan Communist Party was legalized in 1945 by the Allied military occupation of Japan and since then has been a legal political party able to contest elections. In the aftermath of the war, under the guidance of charismatic party chairman Sanzō Nosaka, the party pursued a policy of portraying itself as "lovable."

 No. They practiced fascism/ nationalism/ to take over earth by force.  

Communism would make your Jap-Panties drop in WW2

No. They were imperialist - hence Empire of Japan.

If you had said cannibalism, you might have been nearer the mark:

evidence was gathered, but charges were dropped at the Tokyo war trials.

Nope.  Imperialism and the Code of Bushido.