Surely, Japanese article must be trustworthy when it comes to things related to Kotea! lol

I expected that kind of remarks. Contrary to Western and Korean beliefs, Japanese researchers aren't obsessed with shitting on South Korea 24/7. There's a lot of individuals genuinely interested other languages and cultures, studying things like the Korean speakers in China's Yanbei province. In the article I linked, there are more references to research articles on the topic written by Japanese than what exists in English.