Yasukuni Problem is core issue in relation to Japan's views on the past. The purpose of this article is to provide background information and analysis the importance of the Yasukuni problem. On 28 April 2001 Junichiro Koizumi pledged to make official obeisance visits to Yasukuni Shrine on August, if he will be elected as President of the Liberal Democratic Party. Japanese Prime Minister Koizumi has visited Yasukuni Shrine once a year since taking office. Yasukuni Shrine and its supporters sees World War 2 as a war of self-defense to liberate Asia, and Yasukuni shrined Hideki Tojo and other Class-A criminals in 1978. Prime Minister's official obeisance is not only unconstitutional religious activity forbidden under Article 20 of the constitution, but also South Korea and China say that they cannot overlook visits by Prime Minister to a Shrine that honors the souls of the Class-A criminals. Nevertheless, Prime Minister Koizumi has visited Yasukuni Shrine to pray for future peace every year since taking office. It undermined their friendly relations and confidence toward Japan.