@Aretheus Na, Japanese authors definitely put Japanese culture being above and beyond other countries, especially in Isekai manga where every MC either recreates things like soy sauce, miso, natto, or searches for something similar to them already available, and in some cases spends a crap ton of money trying to acquire rice (or something that is rice like).
But like many Asian countries, South Koreans tend to lean on the xenophobic side. They love white Americans from the US and Canada, and those from developed European countries because they view those countries as being "successful" and rich. But if you're like a refugee, Chinese, and even ethnic Koreans who grew up in China, they view you as being poor and tend to be dismissive or just outright ostracize you. And while Korea will work with Japan for economic and self defense reasons, many Koreans have not forgiven Japan for it's brutal occupation during the early 20th century that Japan still hasn't apologized for and has been actively trying to whitewash that history.
Koreans view the Japanese sort of like villains you see in American movies, they are cunning, but cowardly; pretends to be nice; they can be smart with well thought out plans, but when that plan goes to crap they panic and just make mistake after mistake. And oh yeah, they act like they are honorable, IE their cause is just, but often times resort to backstabbing and needlessly sacrificing their own people for minimal gains.
I won't say that Koreans hate Japanese people, but they just don't have a very good opinion of them because of the country they are from. Just like how a lot of Americans have negative views of people from the Middle East.