It might be filtering down to at least some youth by word of mouth and entertainment. I read comics from Japan, Korea, and China, and it's interesting how they display political rivals. Japan tends to use China, America, and Russia primarily, with America often being not totally an enemy but an arrogant ally. Korea tends to have Japan, North Korea, China, then America playing a similar role. The Chinese ones I do read are often more inwardly focuses, but I have seen America, India, and... hmm I can't recall if I've seen much others, seems to be more about oppressive rich families and regional strife.

This is all subjective based on the stuff I've read of course. In I'm not sure whether you'd call it positive or just being factual, in the Japanese manga Hikaru no Go, China and Korea are both rivals, with Japan being third place among them. Still, since it's Go/igo/baduk/weiqi and not serious international matters, it was more about pride and such. They do have a chapter with Koreans living in Japan having some bitterness towards Japanese opinion of them. Mahouka Kouka also had a section where Americans who grew up in Japan on military bases felt racist pressure from Japanese, but that work also pretty much ignored Korea and had it absorbed into China as a villian.

I digress. I just wanted to day entertainment is great at passing down grudges and prejudice, and the media I've seen still has a lot of it.