X, also known as X/1999, is a Japanese manga series written and illustrated by Clamp, a creative team made up of Satsuki Igarashi, Nanase Ohkawa, Tsubaki Nekoi, and Mokona.

The series follows Kamui Shiro, a young esper who returns home to Tokyo after a six-year absence to face his destiny as the one who will determine the humanity's fate.

It is considered one of Clamp's most iconic works in their early career, having sold more than 12 million copies and garnering mostly positive reviews for its story, large varied cast and appealing illustrations.

[6] The clone Nataku steals the "Sacred Sword" (神剣, Shinken) from Fuma's family temple, with his dying father telling his son that he is Kamui's "twin star".

As these events occur, Tokyo has nearly been destroyed and is flooded, and Kamui and Fuma wield their Sacred Swords needed to clash in the final fight of the war.

[8] Kamui was originally written as a high-school student from Kotori Monou's point of view to appeal to the shōjo audience of young females.

[8] Beyond his penchant for drawing extreme violence, Nagai's writing involves themes like the nature of good and evil and fear, ideas that left an impression on Clamp's writer at an early age.

[13] The ensemble cast, inspired on Kyokutei Bakin's Nansō Satomi Hakkenden,[10] includes Subaru Sumeragi and Seishiro Sakurazuka from Tokyo Babylon, and the main characters of Clamp School Detectives.

Like the biblical city;[16] Clamp's Tokyo is "the habitation of devils, and the hold of every foul spirit, and a cage of every unclean and hateful bird", (Rev.

[12] The Dragons of Heaven take their moniker from the seven seals introduced in Chapter 5 of the Book of Revelation, while the antagonistic Angels allude to the seven celestial beings ordered to "go [their] ways, and pour out the vials of the wrath of God upon the earth" (Rev.

[9] The constant earthquakes the Dragons of Earth cause resulted in a negative backlash from readers and editors because of similar incidents in real life.

[24] The series shares some motifs with apocalyptic literature, like the disclosure of future events through dreams;[25] and establishes a dual nature to its characters and concepts.

[24][25] Sorata Arisugawa is destined to die for a woman; but, unlike Kamui, the warrior monk embraces his preordained future and chooses Arashi Kishu of the Dragons of Heaven as the one for whom he will give his life.

Even with the fatalist atmosphere that persists in the series,[9] Ohkawa is convinced individuals exert control over their destiny the same way they choose between right and wrong.

The series went on hiatus multiple times during its serialization in response to social incidents, including the Great Hanshin earthquake in 1995 and the Kobe child murders in 1997.

[17] Serialization ceased in March 2003, after the editorial staff at Monthly Asuka indicated to Clamp that Kadokawa Shoten was unlikely to publish their planned ending to the series.

[38] On 21 November 1993, SME Records released X2 (ダブルエックス, Daburu Ekkusu), pronounced "Double-X" in English, a short film based on Clamp's manga, set to the music of rock band X Japan.

X2 features a slideshow of X artwork set to a medley of X Japan's songs: "Silent Jealousy," "Kurenai", and "Endless Rain" with the "X" music video directed by Shigeyuki Hayashi.

Written and directed by Kawajiri, An Omen tells the story of the upcoming battles through the prophecies of Kakyō Kuzuki, dreamgazer for the Dragon of Earth, and acts as a primer for viewers unfamiliar with Clamp's manga.

According to the site, "Part of the appeal of the X manga series is its surreal blend of Taoist, Shinto, and even European mysticism with real-world locales and historical landmarks familiar to Japanese fans.

[76][22] Anime News Network noted that while there are no explicit homosexual relationships, the shōjo appeal might give the reader this impression when the male characters interact, something the shônen demographic might not like.

[77] Sequental Tart found Kamui's identity mysterious; he is featured as a caring child to Kotori Monou in a flashback, but he appears as a rude teenager when meeting her again.

[80] Kamui's growing character arc was the subject of a positive mention as Manga News also enjoyed his early appearances and the formation of the Dragons of Heaven as they befriend each other.

[81][82] Reviewers felt Fuma Monou is one of the most brutal antagonists of Clamp's career and in shōjo in general because of this gruesome murder of Kotori and how he then causes earthquakes to destroy Tokyo.

As the second half begins, the same website also noted that the narrative becomes progressively darker because of the number of dead characters as Clamp moves the plot towards the Armageddon; they also mentioned the events that causes all the deaths.

[87] Manga News noted the pair had one of the most anticipated fights in the series because of the long history they have in Tokyo Babylon and called their final duel tragic.

[88] In Manga: The Complete Guide, Jason Thompson wrote "even without a proper ending, the series has a lot going for it", and felt the major storytelling centering around destiny was appealing despite not finding it Clamp's best strength.

[76] Comic Book Bin praised the handling of the fight scenes by the artists especially the backgrounds, which "depict energy and magic unleashed in a fast and furious display".

[79] Because of the manga's long serialization, critics noted that the artwork evolved, making it as appealing as later Clamp works like Tsubasa: Reservoir Chronicle and Angelic Layer.

However, Anime News Network felt the violent imagery portrayed by Clamp throughout earthquakes and murder scenes in X was too disturbing for the Monthly Asuka demographic and cancelled it.