During the ZENON world championships in the year 20XX, a popular card battle game, individuals referred to as "Concodes" join forces with advanced AI partners named "Codeman" to compete. One such Codeman, Eilietta Lash, challenges Souta Azuma, an average high schooler, to compete together. Though he hesitates at first, Souta agrees to the proposal and the duo battles against their first formidable opponents - the renowned Shion Saionji and Ash Claude, who happen to be fellow students at Souta's school.