X, or X/1999 as it is known in the US, is Clamp's latest and greatest manga release in a long line of memorable and unique manga. The manga combines characters from several previous Clamp stories including the famous Tokyo-Babylon and the Clamp Campus Detectives (all grown up now). Within the series are fragments of Western superstition, along with traditional Japanese and exotic Indian folklore. Clamp blends truth and reality so well in this particular series that one almost believes that the story could indeed be possible. Currently, only nine books of the manga are out in either Chinese or Japanese. In addition, X has recently been made into an anime movie. X can mean a cross for crucification or an unknown in an equation. In Japan, X is also the name of a narcotic. The title of the manga series, X, is supposed to be a combination of all three of these meanings. The 1999 portion of X/1999 stands for the year which the end of the world supposedly will occur in the manga. The 1999 was added for Chinese and English translations of the manga. In Japan, the manga is simply titled "X".