isekai

is a subgenre of Japanese high fantasy fiction that revolves around a person or people who are transported to and have to survive in another world. In the new world, the person usually gains formidable powers or some other importance that they did not have in the previous world. The transition between worlds may occur through death and reincarnation or through summoning by an object, god, or person in the alternate world. A common setting is a medieval-like world populated with humans, humanoids, and monsters. In a reverse isekai, a person from another world is transported to Earth.

The concept of isekai started in Japanese folktales, such as the story of Urashima Tarō, and Western fantasy literature. The first modern isekai works were Haruka Takachiho's novel Warrior from Another World and the anime television series Aura Battler Dunbine, while The Twelve Kingdoms and Sword Art Online helped to popularize the genre. Since the 2000s, isekai novels are increasingly published online on websites like Shōsetsuka ni Narō. Isekai is one of the most popular genres of anime and has been noted for its appeal to salarymen as a form of escapism.