X (エックス, ekkusu), aussi appelé X/1999, est un manga du studio CLAMP. D'abord pré-publié périodiquement dans le magazine Monthly Asuka, il a été traduit en français aux éditions Tonkam. L'œuvre devait totaliser 21 volumes, bien que la série soit actuellement inachevée, au stade de 18 volumes parus et 5 autres chapitres prépubliés. Traduit dans de nombreuses langues, le manga a successivement été adapté en film d'animation puis en série télévisée.

It's 1991, the last days of Japan's bubble economy, and money and elegance run through the streets. So do the currents of darkness beneath them, nourishing evil spirits that only the arts of the onmyoji—Japan's legendary occultists—can combat. The two most powerful onmyoji are in the unlikely guises of a handsome young veterinarian, Seishiro, and the teenage heir to the ancient Sumeragi clan, Subaru. (Source: Dark Horse)

Humanity, once a technologically advanced and thriving civilization, has been pushed to the brink of extinction following a cataclysmic war known as the Seven Days of Fire. The remnants of the human race now live in scattered kingdoms to avoid the unrelenting spread of the Sea of Corruption, a colossal forest infested with dangerous mutant insects and fungi that produce poisonous spores. Nausicaä, the sole heir to the throne of the agricultural kingdom Valley of the Wind, is thrust into war after an ally kingdom, the imperialist Torumekia, invades the Dorok Empire. Forced to fight alongside the Torumekian military and their cunning princess Kushana, Nausicaä witnesses firsthand the horrors of war and its effect on both humanity and the environment. With her uncanny charisma and gentle nature, Nausicaä may be the only hope for humanity as the ongoing war and the Sea of Corruption hasten the extinction of mankind. Set against the backdrop of a devastated world, Kaze no Tani no Nausicaä depicts the aftermath of human folly and the immortal power of nature. [Written by MAL Rewrite]