What is isekai?
The term literally means ‘the other world’, which in some sense could be taken to encompass the whole of fantasy fiction, and anything else set on a single planet not named Earth. In practice (despite the occasional, always controversial use of ‘native isekai’ for non-isekai fantasy) the ‘other world’ implies this world as a referent, and a protagonist who is in some sense native to Earth, if at times only in a past life.
So how do we get there? Please, let me know if you find out; escaping this world for another one is my life’s mission. Oikawa Yukio is my icon everywhere for a reason. Traditionally (and still occasionally today), one was summoned by otherworlders, typically for some grand quest involving saving the other world, and sometimes also one’s own - although making one’s way in by accident, while far rarer, was never entirely unheard of.
The afterlife seen in nearly every world religion might in a sense be called “another world” as well, and passage from this world to another is often associated with death, when it is not associated with dreams. The concept of reincarnation is central to the Hindu-Buddhist religious tradition (including Japanese Buddhism), and some older series do play with the concept, memorably in the ending to Fushigi Yuugi, and (drawing the net far more broadly) Inuyasha, where the main character on Earth is the one reincarnated.
(One is also reminded of the 1986 manga Boku no Chikyuu o Mamotte which explores reincarnation extensively through memories of past lives – however, in this case the past lives were spent as scientists on the moon, and while very much a reincarnation manga, it is not really an isekai.)
However, the notion of reincarnating in a world of orcs and dragons simply did not exist until 2012’s Mushoku Tensei and Kono Subarashii Sekai Shukufuku wo! (Re:Zero kara Hajimeru Isekai Seikatsu, although strongly associated with the concept, technically does not qualify; Subaru is summoned before the first time he dies) It has, however, since become so popular that reincarnation isekai, or isekai tensei, have often been conflated with isekai as a whole, and the potential inherent in reincarnation (for one need not come back as a human) has been explored by a variety of series such as Tensei Shitara Slime Datta Ken and Kumo Desu ga, Nani ka?
The category is one with inherently fuzzy boundaries. Being transported into a video game (most often, but not always, a MMORPG with virtual reality elements) is strongly associated with isekai, and forms the background to such popular titles as Overlord and Leadale no Daichi nite. But what then should one make of stories like .hack//SIGN or Sword Art Online when the video game is very much a video game, but the protagonist is trapped all the same? And while it’s easy to dismiss time travel stories as something separate, but related, what of something like Inuyasha, where the world of the past is not the one found in history books, but a fantastic realm where youkai roam freely? For that matter, what of “reverse isekai” stories like Re:Creators or Hataraku Maou-sama, where the travel goes in the other direction?
In any case, my username is birdboy2000, and I am a lifelong fan of the genre. Digimon Adventure is my favorite anime, and its sequels are not far behind. I also love Monster Farm: Enbanseki no Himitsu and Fushigi Yuugi. And I hope you enjoy this website.