Nier is an action role-playing video game developed by Cavia and published by Square Enix in 2010. The music of Nier was composed by Keiichi Okabe with members of his studio, Monaca, Kakeru Ishihama and Keigo Hoashi, and Takafumi Nishimura of Cavia. The soundtrack has inspired the release of four official albums by Square Enix—an official soundtrack album and three albums of arrangements—along with two mini-albums included as pre-order bonuses for the Japanese versions of the game and two licensed EPs of jazz arrangements.
The original soundtrack was highly praised; reviewers noted it as one of the best video game soundtracks of the year, praising the originality of the compositions and the beauty of Emi Evans' vocal work. The first arranged album, while also warmly received, was perceived by critics to be weaker than the original and not long enough to stand up to the expectations created by the success of the original. The first three albums sold well enough to be recorded on the Japanese Oricon music charts, reaching number 24 for the original soundtrack, 59 for the first arranged album, and position number 77 for the second.
The soundtrack for Nier's sequel, Nier: Automata, was released worldwide on March 29, 2017. Returning collaborators include Keiichi Okabe and the Monaca team on composing duties and Emi Evans on vocals, along with several other singers and lyricists. Nier: Automata Original Soundtrack was highly reviewed by critics, and the album peaked at number 2 on the Oricon charts.