" City in the Sky " was the theme song of a very famous Japanese animated film," City in the Sky ", sung by Japanese singer AKB48. After the release of the song, it quickly gained widespread praise and popularity, becoming a classic pop song. There were some interesting stories and legends about the song. One theory was that the song was released in October 2004 from AKB48's single album,"The Moon and Clouds and Wind". The lyrics and melody of this song were very much in line with the theme and atmosphere of the animated film,"City in the Sky", so it quickly became the theme song of the movie. Another theory is that the song was released in July 2006 from AKB48's single album,"Guo Te Shi Na Ku in the Sky." It was said that one of the producers of this song was Aya Yamamoto, a member of AKB48. She liked the theme song of the movie " City in the Sky " very much and decided to write a song for the movie. No matter which theory was correct, the music of " City in the Sky " was closely linked to the movie " City in the Sky " and became a very meaningful piece of work.