Because the Nazis weren't saying that the Japanese need to be destroyed. They weren't saying that all other races need to be destroyed. Ian Kershaw, one of the biggest historians of Hitler and the Third Reich, has stated that Hitler himself greatly admired the Japanese people (and the Chinese) and the pride that he saw that they had in their race. To Hitler different races were supposed to remain separate, create their own countries, and not intermix. In the Japanese he saw a people with similar views and so they made natural allies on different sides of the planet.

Source

Hitler by Ian Kershaw