"X OAV" is a two-episode original anime video adaptation of CLAMP's manga "X," serving as a precursor to the later TV series "X/1999." The story is set in a world on the brink of apocalypse, where the fate of humanity hinges on a prophesied battle between two factions: the Dragons of Heaven, who seek to protect the Earth, and the Dragons of Earth, who aim to destroy it to cleanse the world of humanity's corruption. At the center of this conflict is Kamui Shiro, a young man with immense psychic powers who returns to Tokyo after years of absence following his mother's death.

Kamui's return triggers a series of events as both factions vie for his allegiance. His childhood friends, Fuma and Kotori Monou, are drawn into the conflict, with Fuma representing the Dragons of Earth and Kotori the Dragons of Heaven. Kamui's choice between them becomes a pivotal moment, as his decision will determine the fate of the world. The narrative explores themes of destiny, sacrifice, and the moral ambiguity of choosing between preserving humanity or allowing its destruction for a chance at renewal.

The Dragons of Heaven include characters like Sorata Arisugawa, a cheerful monk with spiritual powers, and Arashi Kishu, a stoic swordswoman. The Dragons of Earth are led by characters such as Seishiro Sakurazuka, a ruthless assassin, and Nataku, a tragic figure created through unethical experimentation. The OAV condenses the manga's complex lore into a concise format, focusing on Kamui's internal struggle and the escalating tension between the factions. The story culminates in a climactic battle that sets the stage for the larger conflict explored in the TV series, leaving key questions unresolved to maintain intrigue.

The OAV's pacing is brisk, emphasizing action and emotional stakes while introducing the core characters and their motivations. It serves as an effective introduction to the "X" universe, providing a snapshot of its apocalyptic themes and intricate character dynamics.