X

Director Rintaro was approached by publisher Kadokawa Shoten to direct the film, and he believes it was because of his earlier work on the 1983 film Harmageddon, even though that film explores different themes from the X manga.

Since Clamp's original manga was unfinished at the time, Rintaro worked with Clamp's head writer Nanase Ohkawa to create a completely alternative, self-contained story, cutting many subplots from the source material to keep it simple.

Rintaro used Asami Watanabe's script as a base but expected that many viewers would reject his approach because it gave Kamui a tragic ending that could clash with fans' personal taste.

X marked the first time Rintaro used computer animation in his career.

The character Shogo Asagi was created exclusively for the movie and did not originate from the manga; an alternate version of him later appeared in Clamp's manga Tsubasa: Reservoir Chronicle as a gang leader.

Kadokawa Shoten editor Seichiro Aoki, who supervised the film to keep the characters faithful to the manga's original style, was surprised to learn that one of the film's characters was modeled after him, using different Japanese characters for the name.

The film's theme song, 'Forever Love' by X Japan, was composed by Yoshiki and also appears on the film's soundtrack; it was later reused by former Japanese Prime Minister Junichiro Koizumi in a 2001 campaign advertisement.

To promote the film, seven audio dramas called The X Character Files were released between June and December 1996, scripted by Nanase Ohkawa and performed by the film's original voice cast, focusing on the thoughts of the Dragons of Heaven and Earth.

The X film is considered the goriest adaptation of the manga, featuring depictions of massive genocide and decapitations that were not shown in the more restrained television series.