is a subgenre of portal fantasy. It includes novels, light novels, films, manga, anime and video games that revolve around a displaced person or people who are transported to and have to survive in another world, such as a fantasy world, virtual world, or parallel universe. Isekai is one of the most popular genres of anime, and Isekai stories share many common tropes – for example, a powerful protagonist who is able to beat most people in the other world by fighting. This plot device typically allows the audience to learn about the new world at the same pace as the protagonist over the course of their quest or lifetime. If the main characters are transported to a game-like world, the genre can overlap with LitRPG.
The concept of isekai started in Japanese folk tales, such as Urashima Tarō. However, the first modern isekai works were Haruka Takachiho's novel Warrior from Another World and Yoshiyuki Tomino's television series Aura Battler Dunbine.
Characteristics
The genre can be divided into two types and . In "transition into another world" stories, the protagonist gets transported to another world (E.g by traveling into it, or being summoned into it). In "reincarnation into another world" stories, the protagonist is sent into another world after dying in the real world. A common method of death is being run over by a truck and dying, spawning the meme of "Truck-kun", a truck which appears in many isekai series that kills the protagonist and the protagonist reincarnates into a different world.
In many examples, the main character is an ordinary person who thrives in their new environment thanks to modern things in the real world being seen as "extraordinary" in the other world. This can be physical characteristics, such as hair or eye color, or normal everyday skills they learned in their previous life such as cooking, engineering, basic education, or medicine, which are far more advanced in the modern, real world than in the world they are sent to. In Sorcerous Stabber Orphen, an entire population of humans appeared in the magically created world, transported from Earth, and were partially mixed with local dragonlike Heavenly Beings.
While the protagonist of a classic isekai work is usually a "chosen hero", there have been a number of alternative takes on the concept. One trend is the protagonist reincarnating into the body of an unimportant side character, or even a villain (as in My Next Life as a Villainess: All Routes Lead to Doom!). There are even instances of protagonists becoming inhuman creatures, such as in That Time I Got Reincarnated as a Slime, where the protagonist reincarnates as a slime with special abilities rather than a human, or even inanimate objects, like a vending machine, or a magical onsen.
Others, known as "reverse isekai follow beings from a fantasy universe who have been transported to or reincarnated into modern-day Earth, including the anime Laidbackers, Gate and Re:Creators.
An offshoot of the isekai genre is the "second chance" or "reincarnation" genre in which the protagonist, upon dying, is transported not to a different world or new body but into their own younger self. With their new knowledge and older intellect, they are able to relive their life avoiding their previous pitfalls. Another offshoot of the genre include the "slow life" approach, where the protagonist was overworked in their previous life, so decides to take it easy in the next. Another offshoot is where the protagonist uses the new world to explore an interest, hobby, or goal they had in the previous world but were unable to achieve, such as studying or opening a business, like in Restaurant to Another World.
In many works, isekai overlaps with the harem and LitRPG genres, where the protagonist gains the affection of several potential love interests, who may or may not be human. One example of this is Harem in the Labyrinth of Another World.
Writing for the Journal of Anime and Manga Studies, Paul Price in his article "A Survey of the Story Elements of Isekai Manga" argues for the existence of four kinds of isekai, based on Farah Mendlesohn's framework of organizing fantasy: "portal-quest", where the protagonist enters the isekai via some kind of portal (Price cites Death March to the Parallel World Rhapsody as an example); "immersive", where no such portal exists and all the action takes place in the other world (Slayers); "intrusion", which are akin to reverse isekai in which the fantastic enters the real world (The Devil Is a Part-Timer!); and "liminal", where the portal becomes a liminal space where the real world and the isekai mix (Restaurant to Another World).