It is true that there is more openness in the younger generations, esp. on the level of interpersonal relationships divorced from politics.  My cousin, who lives in Korea, married a Japanese woman several years ago, which would have been unthinkable a generation or two ago.  But there are still quite a bit of tensions when politics are factored in.  There definitely remains an economic competitiveness between the two countries, especially as S. Korea has overtaken Japan in areas where Japan used to be unquestionably dominant, (e.g., Korean companies like Samsung, LG, Hyundai, and Kia rivaling or surpassing the popularity of their Japanese competitors).  There also remain a number of political tensions between the two countries.  The issue of Korean "comfort women" during WWII is still unresolved, with many Koreans feeling that the Japanese government has failed to adequately take responsibility.  There is also an unresolved dispute over the sovereignty of several islands that lie between Korea and Japan.  There also remains a tendency to downplay or outright ignore any possibility of Japan's influence on Korean culture.  One primary example: Korean martial arts like Taekwondo, Hapkido, Kumdo, and Yudo have many similarities to Karate, Aikido, Kendo, and Judo, and many non-Koreans would argue that they are direct descendants of the Japanese arts.  But talk to any Korean organization or instructor and they will likely deny any Japanese origin.