Saw this comment on an askreddit thread, is it true?
Ive never looked into but in history class we learnt about how during world war 2 propaganda was generated about aliens to incite fear. The propaganda was in relation to aliens that had "slanty" eyes, big heads (intelligent), and spoke and wrote in a funny jibberrish language. much the same as the asian population. :/
The first known description of the Grey Aliens was the Roswell Incident of 1947, where the aliens were described as having over-sized heads and slanted eyes. This was 2 years after ww2 ended, so that depiction would not have been due to American propaganda, and these traits offer no real connection with Japanese stereotypes, and equating big heads with intelligence would be a positive stereotype for the Japanese, so not much use in propaganda.