Caution: dumb and bloated text below. I tried my best to write it and don't know English much. Sorry if it's not easy to understand.
It's just a few words about human psychology actually.
Human kind always founds something to hate at usually it is something different from the original culture or group attributes.
All of this is not new: In almost every Goethe's fiction works, in even ancient text from Greece you can find exactly same hate or oppression (actually you will find whole bunch of modern things in old books like "New generation is wrong and dumber because they don't doing [insert word]", "Anyone who don't know what is [insert word] is a fool", "If you like [insert word] - you are degenerate", etc.). Just topics and entities changes for thousands years.
It both local and global phenomenon. Hate to anime or Japanese notable culture will simply fall of with time and will be displaced with hate to something else. Now even Warhammer have it's own anime. People will get used to it, hating "all Japanese" will be not in trend, or all of those who was caught in motion just grew up and next generations will have something else in mind to make fun of. People will always find an enemy in their head and will group up against it. It happened countless times in all cultures from just local tribes to planet-wide socium and will happen to what you described too.