The war between the Levamme Empire and the Amatsukami Imperium has been raging for years. In the midst of this struggle, the prince of the Levamme Empire declares his love for Juana del Moral and vows to end the war in one year, as part of his marriage proposal. When the Amatsukami catch wind of this, they assault the del Moral residence, targeting Juana's life. As a last-ditch effort to bring the prince his bride, the San Maltilia Airforce employs a mercenary of mixed blood—a bestado—to fly Juana to the prince in secret.

The story focuses on the exploits of rivals Reinhard von Lohengramm and Yang Wen-li, as they rise to power and fame in the Galactic Empire and the Free Planets Alliance, respectively.

There are gamblers out there who even bet their lives as ante. But to secure the integrity of these life-threatening gambles, a violent and powerful organization by the name of "Kagerou" referees these games as a neutral party. Follow Bak Madarame a.k.a. Usogui (The Lie Eater) as he gambles against maniacal opponents at games—such as Escape the Abandoned Building, Old Maid, and Hangman—to ultimately "out-gamble" and control the neutral organization of Kagerou itself.