Siblings Sora and Shiro are inseparable, both in the real world and in the game world. As a team, their individual skills combined make them invincible: Sora, with his astute intuition and penetrating insight; and Shiro, with her remarkable intellect that goes beyond prodigy-level genius. In the real world, they are reclusive and unsocial hikikomori, but in the game world, the siblings together form a blank space, a mysterious group of undefeated online gamers who win every game they play with unbeatable scores. Because the account names of the players are always left empty, they become simply known as "Blank".
One fateful day, after beating a mysterious challenger in a game of online chess, the siblings receive an offer from their opponent to be reborn in his world, a world where everything is determined by games. The siblings, weary of their world, accept his proposal and are transported to the fantasy world of Disboard by Tet, the world's last remaining God and also their former opponent. Together, Sora and Shiro begin their journey in redeeming the weak human race of Imanity and conquering the world to challenge Tet for his title of One True God.