The category is primarily related to Japanese nationalists. Just as right-wing populists in Western win support mainly for their hatred of Muslims(Related Category : Islamophobia), Japan's right-wing populists are gaining support mainly for their hatred of Koreans.
However, not all Japanese nationalists are anti-Korean because Japan is basically more conservative and nationalist than Western countries.(ex. Junichiro Koizumi) but most Japanese nationalists are anti-Korean.
Some Chinese nationalists also tend to be anti-Korean, but the numbers are relatively small compared to those of Japanese nationalists.