Cardrapt, a card game that blends digital and analog components, has become the world’s top card game over the past 25 years due to the unprecedented success of its novels, animations, and other media. “Yamashiro Tenma,” the assistant store manager of a card shop and also a certified judge. On the way home with a large number of pre-constructed decks for sale and his own tournament deck due to a store renovation, Yamashiro Tenma suddenly realized that he had been transported to a medieval world. A world where Cardrapt cards are embodied and utilized in military, political, and commercial situations, and where their value as assets is guaranteed. Tenma realizes that only cards up to Season 6 exist in this world. And most of the methods for summoning cards with special summoning conditions have been lost. This is the story of Tenma, who has more than 40 Season 11 decks while everyone around him is using cards from Season 6 and earlier. It is a story of a man desperately living to secure his safety and position in another world by selling his cards and information to various forces and people.