Typically, Japanese people are kind and generous, and they will closely look at the person's attitudes. The people who are not liked are the people who hate Japan and the Japanese people.
As an example, people who graduated from the Korean School (Chousengakkou) will be given an Anti-Japanese education. I heard from a Korean background person that at a Korean School, if you speak Japanese at the school, you will be beaten by your mates.
Few years ago, there were K-POP trend in Japan, and people were very interested in Korean culture and the Korean people. But when they start knowing that the majority of Korean people have huge hatred towards Japan and also the Japanese people, now many Japanese people are becoming suspicious when they hear the word Korea. It is not because they are racist or not. It is just a rule of thumb or statistics.