Kingdom Hearts χ Back Cover

This is the story of the Chain Chronicle, a book that describes everything that happens in the world. The citizens of the remote continent of Yggd once thought that there was nothing beyond their continent. The continent was divided into several regions, each with its own king. Though there were small skirmishes amongst them, a lord, chosen by the kings in conference, always maintained balance, until the evil Black Army arrived. The Volunteer Army, led by Yuri, was no match for the Black Army. During the fighting, the Lord of Black captures half of the Chain Chronicle, as well as the capital.

Unidentified creatures "Archon" suddenly appear and bring the human beings to a crisis of extinction. A special corps "Goulart Knights" is formed to counter attack Archon. The knights have supernatural power to generate "Holy Grail" from their spirits and battle against Archon.

Another dimension that continues to taint our world, the Shadow World. Humanity is faced with the worst calamity, known as the Shadow Labyrinth. In spite of their desperate attacks, Desir Herrman and his friends lose their battle to the Destruction Dragon, Boromir Napolitan, and the world comes to an end. When Desir is convinced of his end, he opens his eyes... to find himself 13 years in the past. Desir has gone back in time to the enrollment ceremony of Hebrion Academy, the top school for mages in the Empire. To change the future of impending doom, Desir reassembles his friends once again to save the world!

The war between the Kingdoms of Light and Dark has raged on since time began. But the new Prince of Darkness is destined to change that. In the wake of a monster attack, an elderly noble confronts the lone surviving boy. Impressed, he chooses the boy to become his heir to the Throne of Darkness. Meanwhile, in the iridescent clouds above, the Queen of Light and her army are at war with the monsters. But the new Prince of Darkness realizes that Light and Dark must unite and destroy the evil if the world is to survive.