Sacrifice

is the seventh episode of the No Game No Life (Series) anime series. It first aired in Japan on May 21, 2014 on AT-X, and later on May 23, 2014 on other networks.

Plot summary
When planning their strategy against the Werebeasts, the siblings have difficulty in finding a strategy to defeat them. This is due to the fact that the memories of the Werebeasts' challengers regarding the games would erased in case they lost. The siblings are at a loss, until Stephanie entrusts Sora with the key left by the former king, unlocking the hidden door in her grandfather's bedroom which leads to his hidden research on how to outwit the Werebeasts.

Characters
The following characters are listed by the order which they appear in.

Major characters

 * Sora
 * Shiro
 * Stephanie Dola
 * Jibril
 * Chlammy Zell
 * Fiel Nirvalen

Minor characters

 * Speaking roles
 * Former king of Imanity (flashback)
 * Non-speaking roles
 * Stephanie Dola's maids

Events

 * Sora and Shiro research on how to defeat the Werebeasts
 * Stephanie deliberates whether she should entrust her key to Sora, which she eventually does
 * Sora and Shiro unlock the door to the previous king's secret room, which contains logs of his challenges with the Werebeasts.

Key differences from light novel
In the light novel,
 * The scene with Chlammy and Fiel did not occur.
 * The location which Stephanie kept her key was never mentioned, but it was kept in the flower she wears on her head in the anime.
 * Stephanie was more shocked when Sora and Shiro explained how they found the secret room which the key opens, whereas in the anime, she was busy brooding over the possibility that the stash was pornographic materials for a much longer time.

Trivia

 * A reference to Gendo Ikari from Neon Genesis Evangelion appears in a scene with Sora.
 * The preview for Episode 08 references Sid Meier's Civilization IV.
 * Jibril can be seen with a Yandere face, a meme originating from Mirai Nikki's female protagonist, Gasai Yuno.
 * When Stephanie Dola is infuriated at Jibril for calling her Dola-chan, Stephanie turns into a "Doraemon" look-alike, which is a reference to Doraemon from the anime Doraemon.
 * Sora does "The Gendo Pose" (complete with glasses), while asking Jibril information about the Eastern Federation.
 * The sailor outfit Shiro wears in the library resembles Ryuko's uniform from Kill la Kill.