Former X Japan guitarist HIDE died in 1998. After the re-union, the band still considers him a member and introduces him at every concert, using also in live performances some of HIDE's recorded guitar parts.

Their original name was just X in the eighties and first nineties, when they started their career as one of the first heavy metal bands in Japan. When they began having international success they changed to X Japan, in order to be easily recognized and to avoid the risk of being confused with other international bands that could have the same name. X Japan were among the first Japanese bands to achieve mainstream success and they are considered as fundamental for the development of the heavy metal scene in their country and also as seminal for the "Visual kei" movement that characterizes the style of many Japanese rock musicians and bands (glamorous look, excessively large hairstyles, androgynous aesthetics, flamboyant make-up and costumes). X Japan sold over 30 million records and 2 million videos throughout their career. In the first and middle 80s they mainly released singles and demos through indipendent labels, their first full-length studio album dates 1988 and was released through Extasy Records, label founded by X Japan leader and founder Yoshiki Hayashi. X Japan then kept on recording studio and live albums and videos until their disbandment in 1997. Also their musical style evolved, from the original power metal with elements of glam and speed metal to a more experimental genre that touched progressive and symphonic metal. After many years (and many different projects for all X Japan members), when all seemed lost, in 2007 X Japan decided to re-unite, performing many concerts thoughout their country and abroad and realizing the dream of a first North American tour in 2010. The band activity continues and actual projects are for new studio albums and new world tours.