Zenonzard: THE ANIMATION - Episode 0

The year 20XX. Humans called <Concodes> and ultra-high-performance AI called <Codeman> team up as buddies to compete in the card battle game ZENOZARD. People are going wild with excitement at the world championships, THE ZENON. One day, Sota Azuma, an average high school student, is challenged to a battle by a mysterious woman, Eilietta Lash. She reveals that she’s a Codeman and that her intent is to team up with Sota and participate in THE ZENON. Sota reluctantly agrees. Sota and Eilietta’s first opponent turns out to be the super-famous player Shion Saionji, who attends Sota’s school, and her buddy, Ash Claude.

Synopsis from Anime News Network