Ties

Regardless of what has happened, I would still go to Japan again if I get another chance. But next time I would go to Kansai region and Kyoto instead of Tokyo. I think I've seen enough of Tokyo already. I want to check Himeji and Osaka castles. Also check the different Japanese cuisine there, like Kobe beef :)
The best would really be to live there for a year or so, but that is highly unlikely to happen. Living and working in Japan would allow me to go to different regions in Japan on the weekends and also allow me to remember my mediocre Japanese which I had long forgotten. Maybe even pickup Shamisen classes. This would also make me geographically closer to Korea, allowing me to make frequent trips to there to be more aware of my own culture and also visit my family in Korea. Bottom line is that I can't move to Korea until I'm 35 yrs old, before that is asking to be drafted to the Korean army. Maybe a decade ago I could have served, but now it's too late. At 30, wasting 2 years in the military would be counterproductive.
There are so many things I want to check in Japan, no wonder I want to live there. Of course I would get the "traitor" status for not having the same passion for Korea as I have for Japan, but what the hell. I want to to check Gion Matsuri and eat yakitori, I want to check the castles, the other regional foods in Japan. I guess its hard for Koreans to understand why a Korean wants to check Japanese culture so bad. I think is still a taboo to some extent. Koreans are very proud people and because of that there is a lot of resentment to old Imperial Japan for annexation of Korea and Japan's government's inability to admit certain war crimes from the WWII.
The late imperial Korea is marred with Japanese meddling in Korean imperial lineage and internal affairs. It's understandable, like in Japan, the Imperial family is a symbol of their culture, state and pride, and Japanese attempts to dilute the Korean Imperial lineage through intermarrying Korean Imperial members to lower Japanese Imperial members as unforgiving. Though, is it really a bad thing? Shouldn't this bring people together? Maybe not back then, but today? The marriage of Prince Eun of Korea to Princess Masako of Nashimoto of Japan under different circumstances might have been a good thing to bring people together, but his military service to Japanese Imperial Army during Japanese annexation of Korea is almost seen a treason. He eventually gave up his Korean citizenship and picked up Japanese citizenship compounding his treasonous status.
Japanese Annexation of Korea was unavoidable, considering that for centuries Korea had been weakened by fending off the Chinese invasion from the west, and then the isolationist policy left the Korean military very outdated. Korea always had a superior military power when compared to Japan, until Japan took rapid military modernization during Meiji Restoration acquiring western military equipment and training, while this, Korean military declined with its isolationist policy.
But past is past, whats done is done. The key is look forward and bridge gaps. Like Korea-Japan World Cup. I find it interesting in regards to K-pop and K-drama ratings in Japan, although not the best way, its a way to spark interest in Japan about Korea. Supposedly, after airing a Korean telenovela called "Winter Sonata" in Japan through NHK, polls suggested that interest in Korean culture by Japanese went up by a large margin, it also triggered a large tourism boom from Japanese visiting Korea and it also caused an increase of Japanese trying Korean proficiency exams. Granted, telenovela are trash, unrealistic view about Koreans, but its a start.
Maybe two generations from now, things will be different. I think the animosity is mostly from extremist and people that has direct or indirect lingering issues with the annexation and WWII.

Pics lifted from wikipedia