Isekai Quartet (Japanese: 異世界かるてっと, Hepburn: Isekai Karutetto) is a Japanese anime series that is a chibi-style crossover between the light novel series KonoSuba, Overlord, Re:Zero − Starting Life in Another World and The Saga of Tanya the Evil, all published by Kadokawa Corporation.

An anime film set after the second season, titled Isekai Quartet: The Movie – Another World, was released in June 2022.

The protagonists from KonoSuba, Overlord, Re:Zero, and The Saga of Tanya the Evil all press the button occasionally, unintentionally and move to a parallel world — another brand new isekai — where a new story featuring high school life begins.

[14] Hino, Fukushima, Kobayashi and Yūki perform the second season's opening theme song "Isekai Showtime" (異世界ショータイム, Isekai Shōtaimu), while Sumire Uesaka, Rie Takahashi, Inori Minase, and Saori Hayami perform the second season's ending theme song, "Ponkotsu!

[22][23] The film's theme song is "Melodic Road Movie" (メロディックロードムービー, Merodikku Rōdo Mūbī) performed by Konomi Suzuki and featuring Kashitarō Itō.