All the power in the world of Aitra is condensed in the "contract card" - some people use it to summon flames, some use it to make a contract with the dragon, and some can even tamper with the weather and reverse life and death. However, after the "Card Catastrophe" a hundred years ago, half of the ancient cards disappeared, and the "Saint Seal Master" family with top power was almost destroyed.
Lin En, a young man who was ridiculed as the "Unsealable One", has only been able to use an inactivated bronze card since he was a child. However, during an escape, he accidentally awakened the sleeping soul in the card - it was the "rune afterimage" from before the catastrophe, and he was the only one who knew the secret of the "Blank Throne". At the same time, Elena, a girl known as the "Holy Seal Orthodox", is shouldering the family's mission to find the missing "Origin Card", but she discovers that the secret guarded by the family is the cause of the catastrophe.
When Linn's "Remnant Seal Card" resonates with Elena's "Saint Seal Card", the two are forced to team up to travel through the Cursed Forest, pass the life and death trial of the Card Academy, and fight against the "Dark Seal Order" who attempts to seize the throne. They gradually discovered that the so-called "contract cards" were not the power created by humans at all, but the "shackles of rules" left to the world by the ancient gods, and the real owner of the "Blank Throne" would determine the survival or destruction of the world of Aitra.
