No Game No Life

Synopsis

Believing Shiro's memories have been tampered with, Jibril arranges a chess game to remove the memories regarding Sora; Shiro decides her memories are real and wins the match. After investigating, Shiro recalls Sora arranged a game of reversi with Kurami; the game's pieces consist of the components making up Sora and Kurami's identity. Having lost most of his pieces, Sora was nearly erased from existence but the last three pieces allow Shiro to keep her memories of him. Shiro finds the pieces in her room and places them on an invisible board, winning the game and restoring Sora. From his victory, Sora shares his memories with Kurami, allowing them to form an alliance, and gains the right to manipulate Fil's memories. (Source: Wikipedia)