No Game No Life
Siblings Sora and Shiro are inseparable, both in the real world and in the game world. Their individual skills combined make them an invincible team: 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 hikikomori, reclusive and unsocial, but in the game world,
the siblings together form 『 』 (Kūhaku (空白?, lit. “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, Disboard – a fantasy world where everything is determined by games. When they accept the proposal, Sora and Shiro are summoned to Disboard by the world’s God, Tet, who they discover to also be 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. (source: Wikipedia)
The song is called ‘Oracion’ by Ai Kayano