How Does X Connect to Tsubasa?
CLAMP never finished X, so they did something stranger: they moved its cast into another universe and let them live there.
Tsubasa: Reservoir Chronicle (2003 to 2009) is CLAMP's crossover epic, built on the star-system idea that the same souls recur across worlds with the same faces and different lives. The X cast is its largest single inheritance, and the Tokyo arc is where they land: an acid-rain apocalypse that reads like X's own ending rebuilt as a setting.
These are alternate versions, not continuations. The relationships are rearranged on purpose, and the rearrangements are the point.
THE TOKYO ARC
Two factions, one reservoirCity Hall faction
Alternate Dragons of Earth, led by the vampire Kamui, guard the water beneath the Tokyo government building. Kazuki, the girl Nataku was cloned from in X, takes the seventh seat that Seishiro holds in the original.
Tower faction
Alternate Dragons of Heaven, led by Fuma, hold the Tokyo Tower side of the city. Daisuke Saiki takes the seat held in X by his uncle Seiichiro Aoki’s counterpart line.
The water war
The two camps fight over the last clean water in a drowned, corroded Tokyo: the end of the world X prophesied, shown from inside, as a place people simply live.
THE VAMPIRE TWINS
Kamui and Subaru, rewrittenA new twin
In Tokyo Babylon and X, Subaru’s twin is his sister Hokuto. In Tsubasa, CLAMP make Kamui and Subaru the twins: two vampires travelling between worlds, which fuses the two emotional centers of X into one bond.
The hunter
Seishiro crosses worlds hunting them, having traded his right eye to the witch Yuko for the power to travel, a price that rhymes with the eye Subaru takes from him in X. Subaru once gave Seishiro his blood, making the hunter dependent on the prey he chases.
Fuma, at peace
Tsubasa’s Fuma is Seishiro’s younger brother, a cheerful treasure hunter and friend to the heroes. After X, the gentlest joke CLAMP could play was letting Fuma be kind and stay that way.
THE WIDER WEB
X inside the CLAMP universeTokyo Babylon
Subaru, Hokuto, and Seishiro arrive in X with their tragedy already written; X is, among other things, the sequel Tokyo Babylon never had room to be.
CLAMP School Detectives
The CLAMP Campus and its chairman Nokoru Imonoyama shelter Kamui in X, one of many threads tying the apocalypse to CLAMP’s lightest series.
Inuki travels too
Yuzuriha’s spirit dog Inuki appears in Tsubasa as well, one of the smallest and most telling carry-overs.