Isekai is a genre of fantasy anime where a character travels from the world they know to an unfamiliar one. Typically, isekai series will place a person in a magical realm of fantasy and/or terror, though occasionally it happens in reverse. The Devil Is a Part-Timer!, for instance, shows what happens when Satan must adjust to life in Tokyo - which means getting a job in fast food. Some isekai anime, like Sword Art Online and Log Horizon, take place in virtual worlds or MMORPGs, while others feature real worlds with real people living in them.
When it comes to the best isekai anime, the finest series present viewers with worlds just as compelling as any protagonist. If you're looking for an anime to transport you to another world, try one of these.