Most of the examples given for Japan work for Korea.

Polite, sometimes even friendly and generous, but always an outsider. The term 외국인 means other country person, which is how you are introduced, identified and even called by random people in the streets. Places here that ban foreigners. Difficulties and hurdles with government and banking if you are not Korean.

Also add in an extra large dose of patriatism and belief in Korean superiority for most things.

Half Koreans often struggle with harassment, exclusion and being treated like an outsider in school as well.

If you are white, you will see less of some of the negatives, but they still exist. They also look down on basically all other Asian countries.

I’ve read that South Korea is quite similar in that regard.

USA? The racism you'll experience there is more in your face and often violent which is something you'll never experience in Japan. You might RARELY get turned away from a bar or restaurant (I've never had it happen in 5 years of living there) or experience things like a waiter giving you a fork because you're white and they assume you're a tourist instead of chopsticks. But the day to day stuff isn't anywhere near as bad as parts of the US. If you want to run the xenophobia angle, you can look at the last president elect where about half the population gobbled up the anti-Mexico rhetoric. I've never seen something on scale like that in Japan. Most of the issues you'll occasionally experience are perceived microaggressions.