The National Anthem of Japan (日本の国歌)
Japan's national anthem is called 'Kimigayo.'
It was legally recognized in 1999 with the passage of the 'Law Regarding the National Flag and National Anthem' on August 13, 1999.
Summary
Kimigayo contains lyrics based on a waka poem written in the Heian period which are sung to a melody composed by Hiromori HAYASHI during the Meiji period, since which time it has been considered to be the national anthem. There was debate regarding the relevance of Kimigayo after the World War II but it was officially designated Japan's national anthem by law.
This legislation made it possible to change the national anthem by changes to the law.
Other attempts
After World War II, at the beginning of the 1950s, the Japan Teachers Union and Kotobukiya (now Suntory) respectively accepted entries, selected and announced 'Shinkokuminka' (new national anthems), in an attempt to create a new 'kokuminka' (national anthem). Kotobukiya selected 'Warera Aisu' (We Love our Country) and the Japan Teachers Union selected 'Midori no Sanga' (Green Mountains and Rivers). Neither went on to become established as national anthem.