Isekai Quartet

is a Japanese anime series that serves as a chibi-style crossover between Kadokawa's isekai-genre light novels. There are currently two seasons, with a third confirmed.

Plot
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. 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!

Season Two sees them being joined by protagonists from The Rising of the Shield Hero, with the protagonists from Cautious Hero: The Hero Is Overpowered but Overly Cautious making a small appearance.

Official

 * [http://isekai-quartet.com/ Official Site (JP)
 * Crunchyroll
 * Funimation
 * Twitter (@isekai_quartet)

Other Wikis

 * w:c:KonoSuba
 * w:c:Overlord
 * w:c:ReZero
 * w:c:Youjo-Senki