Japanese police said they arrested a South Korean national holding a banner carrying political messages on Wednesday for allegedly obstructing an annual spring festival at Tokyo's Yasukuni Shrine.  The shrine honors Japan's 2.5 million war dead, including convicted criminals.  Victims of Japanese aggression and imperialism before and during World War II , especially China and the Koreas, often perceive visits to the shrine as demonstrating a lack of remorse about Japan's wartime past.  The 64-year-old held up a banner carrying messages including one urging "war criminals" to stop praying at the shrine, and another making territorial claims on an island disputed between Japan and South Korea .  According to the Japanese Kyodo news agency, the man stood at the main gate in front of the shrine in front of vehicles that were carrying messengers from the emperor.…