No Game No Life, Vol. 7 (light novel) — Yuu Kamiya

At the end of the eternal Great War, the world where everything is decided by games, "Disboard," is born as the means to an end are changed from violence and force to games and wagers. But winners still trample losers, and the victims pile up. A young shrine maiden laughs at how nothing has changed. As the gamer siblings Sora and Shiro play a dice game where the number of dice you have is determined by your age, everyone seems to be against the pair. Will they survive, or will they lose the game--and their lives?