A response to the article, "Japan's ruling party head apologizes for his country's wartime crimes in Korea":
To understand Korean society, one must understand that there exists a deep-rooted anti-Japanese sentiment that stems from historical reasons. One of the two major historical events is Toyotomi Hideyoshi's invasion of Chosun from 1592-1598, referred to as 임진왜란, or the Imjin Invasions in Korean. It was the most influential event in the history of the Chosun dynasty, because Korea not only resulted in a huge number of casualties, but also in substantial cultural, economic, and infrastructural damage, including the large reduction in arable land, destruction and confiscation of significant artwork and artifacts, and abductions of Korean artisans and technicians. The other event is the Japanese colonization of Korea from 1910 to 1945, during which the Japanese colonial government tried to wipe out the Korean language and culture with a "cultural assimilation" policy (aka "cultural genocide" as quoted by Japanese scholar Yuji Ishida)--imagine that you are forbidden to write or speak your native language in schools, businesses, or public places under penalty of death, forced to use another family name, and forced believe a new religion by a foreign government--along with committing various war crimes (including forcibly recruiting Korean girls to serve as "comfort women" to the Japanese army, experimenting on humans in their notorious Unit 731).
The belligerent attitude of Koreans toward Japanese people (and their affinity towards movies like "Japan Sinks" and books that criticize Japan) is caused, more or less, by these historical reasons (and in the present, the controversy surrounding their rewriting of history textbooks that give a one-sided view). The fact that a high-ranking Japanese government official expressed regret that his predecessors have not for Japan's historical mistakes signals a changing wind in Korea-Japan relations from irreconcilable enemies/rivals to that of friendly acquaintances...or I hope so, at least.
---Jeeyoon Yu, C'11