"They did the same thing" is not a reason for anything. An eye for an eye makes the world blind. And hating people because politicians are idiots is unreasonable. I agree with nahadef that these debates are pointless for an average person, especially because we can only form an opinion based on what we gathered from the internet, or our environment. One cannot know the truth for sure without inspecting all the evidence both parties think to be proving their right. Altough Japanese politicians being ignorant about WWII, and acting in a provoking manner in these island disputes doesn't help much, I believe I read about some quite immature Korean (politicians') answers to that.
Let me tell you about all the people I, as a Hungarian, could hate because of "what they did to us" in the past: Austrians, Czehs, Slovakians, Romanians, Serbians, Croatians, French, Russians, Germans, Mongolians, Italians, and Turkish. And most of those happened in the last 100 years. When I was probably about 13-14 years old, I used to participate in useless debates about Transylvania and Slovakia, or what the Romanian Army did in WWI. But I stopped doing that because I realized it was dumb and pointless.
Oh, just one more friendly advice: you are addressing the readers of the forum here, not "Japan", or "the Japanese people". Starting with "you have no rights to the islands" is ultimately true, as I don't remember Jref and/or its readers claiming ownership over any islands. This just makes you look aggressive, which in turn makes people ignore you. If you don't want to be percieved as a "bitter and biased person on the internet", don't act like one.