Isekai Quartet

Isekai Quartet (異世界かるてっと, Isekai Karutetto) is a Japanese anime series that serves as a chibi-style crossover between the series KonoSuba, Overlord, Re:Zero − Starting Life in Another World, Saga of Tanya the Evil and The Rising of the Shield Hero, all published by Kadokawa Corporation. It first aired on the 9th April 2019.

A Season 2, titled Isekai Quartet 2, was announced on October 5, 2019, and was released on January 14, 2020, adding characters from The Rising of the Shield Hero as protagonists. A third Season was announced at the end of Season 2. The series first theatrical production, Isekai Quartet The Movie -Another World-, was announced on July 6, 2021 and set to be released in 2022.

The series is produced by Kadokawa, with Studio PuYUKAI on animation. The official site is isekai-quartet.com.

Synopsis
One day, a magic button suddenly appears. The protagonists from KonoSuba, Overlord, Re:Zero − Starting Life in Another World, and 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. Soon, they are joined by protagonists from The Rising of the Shield Hero with cameos from the Cautious Hero: The Hero Is Overpowered but Overly Cautious series. With no way of escaping, the characters must lead a normal school life and make acquaintances with the others. One thing is certain: the classroom full of fan-favourite eccentric personalities never gets boring!

Staff and Cast
The cast of the original series have come to voice their respective characters on Isekai Quartet. Asini Minoru is the director/screenwriter; Takahara Minoru is the character designer and general director.

Theme Songs

 * Opening Season 1 : Isekai Quartet (song)
 * Ending Season 1 : Isekai Girls Talk
 * Opening Season 2 : Isekai Showtime
 * Ending Season 2 : Defective! Isekai Theater

Isekai Quartet Adventure! Action Game (2021)
'''Isekai Quartet Adventure! Action Game''' (異世界かるてっと　冒険！あくしょんげーむ) is a single-player video game produced by Gotcha Gotcha Games for the Nintendo Switch. It was released on June 17, 2021 and available online for download.

Isekai Quartet The Movie -Another World- (2022)
Isekai Quartet The Movie -Another World- (異世界かるてっと ~ あなぎーあーるど ~) is an upcoming movie based on the anime crossover series Isekai Quartet series. The movie is scheduled to be released in 2022.

Trivia

 * Overlord (ぷれぷれぷれあです, en: Pure Pure Pleiades), Re:ZERO (Re:プチから始める異世界生活, en: Re: PETIT ~Starting Life in Another World from PETIT~), and Youjo Senki (ようじょしぇんき, en: Youjo Shenki), all have their own separate chibi series: the staff who made these worked together on Isekai Quartet.