X (エックス), also known as X/1999, is a Japanese shōjo manga series created by Clamp, a creative team made up by Satsuki Igarashi, Nanase Ohkawa, Tsubaki Nekoi, and Mokona. It premiered in Monthly Asuka's May 1992 issue and ran there until the magazine's editors showed concern with the increasingly violent stories and the series went on long-term hiatus in March 2003. The story takes place at the end of days, in the year 1999. The series follows Kamui Shirō, a young esper who returns home to Tokyo after a six-year absence to face his destiny as the one who will determine humanity's fate.

Writer and Illustrator: Clamp (クランプ), is an all-female Japanese manga artist group that formed in the mid-1980s. Almost 100 million Clamp tankōbon copies have been sold worldwide as of October 2007.

Genre: Action, Romance, Supernatural, Apocalyptic fiction, Tragedy

Age: 16+