Hiromu Arakawa, award-winning manga creator of the best-selling smash hit Fullmetal Alchemist, draws readers into an intricate new web of magic, intrigue, and life-or-death stakes! In a world where certain humans command mighty supernatural duos called Daemons, it is the birthright of 'the children who sunder day and night' - twins Yuru and Asa - to rule over these powerful entities. Separated from a young age and unaware of the truth of their birth, brother and sister must fight to make their way back to each other, claim their birthright, and save the world... The bizarre and mysterious clash as a Daemon-on-Daemon battle ensues! Yuru's serene and simple mountain life is turned upside-down by a surprise attack on his village by a young woman claiming to be none other than his actual twin sister Asa. And it's only with the help of the Daemons the Divine Left and Right - powerful supernatural guardians he can now command - as well as two of the village's loyal liaisons, that Yuru manages to escape to the world down the mountain. But while his new allies aim to hide Yuru among the modern world's masses, the headstrong teen has other ideas. In search of answers, he slips away in the dark of night only to land smack in a trap set by Asa's coconspirators, the Kagemori clan!