Kouichi Sanada and Kazuki Aihara's childhood friend Mao Mizusawa has returned after living in France for a couple of years. Kouichi is surprised to learn that, since her parents are remaining overseas for the time being, his mother has agreed to let Mao stay with them. The three friends help each other deal with the ups and downs of high school romance.
The year is 2661 CE. Ten years ago, Bashin Dan became the trigger that stopped the Earth from resetting itself. On the anniversary of this sacrifice, Barone and Clackey hold a conference, celebrating the union of Mazoku and humanity, and also Dan's feats.
However, beneath that peace, an organization named Cardinal Sign advocates for the subjugation of Mazoku and human supremacy. They resort to terrorist attacks, violence, and have somehow obtained the 12 Zodiac X-Rares which ought to have vanished together with Dan.
Amidst all this chaos, the bearers of the core's light feel a weird sensation, one that they've felt before. What could be the meaning of it, and what is the meaning behind the card that appeared within their decks, named "The Clash King's Miracle"?