X Japan is a Japanese band founded in 1982 by Toshimitsu "Toshi" Deyama and Yoshiki Hayashi. Originally named X, the group achieved its breakthrough success in 1989 with the release of their second album Blue Blood. They started out as a power/speed metal band and later gravitated towards a progressive sound, at all times retaining an emphasis on ballads. After three more albums, X Japan disbanded in 1997.

Besides being one of the first Japanese acts to achieve mainstream success while on an independent label, the group is widely credited for pioneering the visual kei movement, though most of the group's members toned down their on-stage attire in later years. They were formerly known for their excessively large hairstyles resembling fountains. As of 2007, the band has sold over twenty million records and over two million home videos.

On 4 June 2007 it was announced the band would reunite with a new song released via digital download in January 2008 and live performances scheduled for March and May.