Any devoted manga or light novel fan knows the gist of what isekai is: a story in which a “normal” person dies and ends up in a fantasy setting. 

Isekai has dominated the manga and light novel markets in recent years. Publishers are releasing hundreds of volumes of isekai titles a year.

Isekai has oversaturated both markets to the point where practically everyone is sick of it.

Some of the most popular titles include That Time I Got Reincarnated as Slime, Rising of the Shield Hero and Overlord. They all hold the same premise: A protagonist is reincarnated or summoned to a new world and is chosen as a hero or a monster that will save the world. 

The rise of the genre is connected heavily with novel-posting sites that became popular in the early to mid-2010s, where users could freely post stories. Stories that become popular on these platforms have been scouted by Japanese publishers and turned into light novels, which are then adapted into manga because manga sells very well. 

One reason that people love the isekai genre is because it largely stems from video games and anime. Many in the current generation of readers are familiar with them and it also offers an escapist fantasy for many. 

In the U.S. and other international markets, where many manga readers tend to be fans of Japanese culture, they make up a large portion of the manga market.

While isekai has led the way in recent years, manga lovers and critics are certain that the manga market as a whole will continue to grow regardless of such oversaturation of isekai.

However, isekai still continues to delight its fans, inspire a culture of online novel writing and offer a stream of new material for international devotees of Japanese pop culture.