Actually this is nothing new; anime fans have been doing this for decades!
No, really- when I was a senior in high school in 1998-1999, someone told me that there was a girl name "Michi" who was all into anime. He tells me that Michi is Japanese and she had the dude give me her website. I go home and look at the site, and see that it is a poorly-made fansite for a Sailor Moon character named "Michiru Kaiou." This character has green hair.
The next day in school, my classmate tells me that Michi is sitting at a table across the room at lunch. I look over and don't see any Asians sitting there, but there is a blue-eyed, blonde haired white girl with a bad green hair dye job sitting there looking stupid. And that of course, was "Michi."
She was "Japanese."She was telling everyone that she was a quarter Japanese or some bullshit...because she liked a fucking cartoon character. I told my classmate how full of shit she was and that she appeared to have dyed her hair because of this character and he laughed pretty hard. Never heard him talk about her again and I never talked to this girl since she was an underclassman and I didn't have any classes with her, but I'd occasionally run into her or be around and hear her gushing about anime. Every time she would see me, her face would turn red and she'd stop talking about it, lol. I worked at a video game store at the time and had encountered plenty of otaku-types, but this was the first time I'd ever seen a weeb
in the wild, so the memory still stands out.