Isekai Quartet Episode 1: Come Together! Quartet
Episode 1 of 12 of Isekai Quartet, aired April 10, 2019, 12 minutes. Available with English subtitles and dub where released.
Episode summary
Mysterious buttons appear in the worlds of Tanya the Evil, KonoSuba, Overlord, and Re:Zero. When the characters push them, they're taken to a place they'd never imagined...