I suppose it may not be right to hate an entire people, but it's definitely understandable. I think if another country attacks your country, it's understandable to hate everybody who lives in the attacking country. Like I'm sure the French probably weren't too enamored of Germans in the years right after World War II.
Exactly. To live under occupation, to be subjugated, beaten, tortured, have your children taken away, to see your whole culture destroyed, and dismissed for so many decades it's more than understandable that you would have no love or forgiveness for those responsible. There is no being politically correct in this, there is no 'oh it's racist for the Koreans to hate the Japanese', it is what it is. We should get on our knees thankful we don't know what this was like. It doesn't help that modern Japan is ambivalent even now about the apologies and compensation due to Korean and others. The OP is talking about the Japanese and Koreans of that time, not modern people but of the time of the atrocities etc, looking at it from a distance of many years perhaps some cannot understand the feelings of those involved, which is a shame because not understanding and remembering means not learning and not learning means repeating those horrors.
We have people in our country who still suffer because of what was done to them by the Japanese.
Flashbacks terror for Japanese prison camp survivor
BBC - WW2 People's War - A Woman Prisoner of the Japanese