We're not their colony anymore, and they can't push us around like this. Japan occupied Korea with great brutality from 1910 to 1945, which many Koreans still recall bitterly. Relations have gradually warmed, but as late as 1999 feelings were still so raw that Japanese music and most Japanese movies were banned in South Korea. Their rivalry to host the World Cup got to be alarmingly intense before FIFA opted for the co-host scheme, which thrilled neither country. It's very important for the relationship of the two countries.
Japanese fans seem somewhat less passionate about the name flap.
At the bottom of the World Cup lies the concept of peace. Japan should be more confident and proud in order to preach peace to the world. Both see the event as an opportunity to showcase their country, thus the spreading of venues so many cities can share the spotlight. They see it also as an opportunity to build their professional soccer leagues, just as the U.S. victory in the 1999 Women's World Cup was a big boost for women's soccer in the United States. Although South Korea's men's team is consistently strong, the Asian leagues still are considered not as good as those in Latin America and Europe.