"Tsubasa: Spring Thunder" is a two-episode OVA that serves as a continuation of the "Tsubasa: Reservoir Chronicle" series, adapting the "Spring Thunder" arc from the manga. The story takes place after the events of the second anime series and focuses on the ongoing journey of Syaoran, Sakura, Fai, and Kurogane as they traverse dimensions to restore Sakura's lost memories. The group arrives in the country of Shura, a war-torn land divided between two factions: the Shura and the Oto. The conflict is rooted in a prophecy that foretells the destruction of the world unless a chosen individual, known as the "Child of Prophecy," is sacrificed.

Syaoran and his companions become entangled in the war when they encounter Princess Tomoyo, a key figure in the Shura faction, and her loyal retainer, Fūma. Tomoyo believes that Sakura may be the Child of Prophecy, destined to bring either salvation or ruin to Shura. As tensions escalate, Syaoran is forced to confront his own identity and the growing darkness within him, a consequence of his fragmented soul and the manipulations of Fei Wang Reed, the series' overarching antagonist. The narrative explores themes of sacrifice, destiny, and the moral complexities of war, as the characters grapple with their roles in the unfolding tragedy.

The OVA delves deeper into the lore of the "Tsubasa" universe, revealing connections between the characters and the larger multiverse. Syaoran's internal struggle becomes a focal point, as his dual nature—part original, part clone—creates a rift between his desire to protect Sakura and his darker impulses. The story also highlights the bond between the main characters, particularly Syaoran and Sakura, whose relationship is tested by the weight of their shared destiny. The OVA concludes with a cliffhanger, setting the stage for further developments in the manga and leaving key questions unresolved. The animation maintains the visual style of the previous series, with detailed character designs and fluid action sequences that complement the dramatic tone of the narrative.