Isekai Quartet

Isekai Quartet (異世界かるてっと) is an upcoming anime crossover spin-off that is set to air in April 2019. It is a crossover series that includes four major light novel works that boast a cumulative total of over 16 million copies in the total series, and boasting a total sales of more than 500,000 BD & DVD series : Overlord, KonoSuba (この素晴らしい世界に祝福を！), Re:Zero − Starting Life in Another World (ゼロから始める異世界生活), and Youjo Senki(幼女戦記).

The series is produced by Kadokawa and the Studios in charge of animation will be Studio PuYUKAI. Asini Minoru will be the director/screenwriter; Takahara Minoru will be the character designer and general director.

Summary
A mysterious switch appeared one day. When pressing it, they were sent to a different alternative world!! There are also characters from other alternative worlds gathered together...!?

Trivia

 * Staff who created Pure Pure Pleiades (ぷれぷれぷれあです), Re:PETIT ~Starting Life in Another World from PETIT~ (Re:プチから始める異世界生活), Youjo Shenki (ようじょしぇんき) will also be working on this joint animation series.