Isekai

Isekai is a term from Japanese popular fiction referring to a narrative in which the main character moves from the real world into a different world. The word is literally “another world” in Japanese. In most isekai stories, the protagonist is transported, reborn, or trapped in a parallel realm, often a fantasy setting with magic and monsters. Once there, they must navigate unfamiliar rules, societies, and power structures, frequently gaining abilities or equipment that help them survive or shape the new world. The mode of entry can vary, including magical portals, death and reincarnation, or summoning from another dimension.

Origins and development

While related to portal fantasy and reincarnation fiction, the modern isekai genre grew from Japanese web novels and light novels in the late 20th and early 21st centuries. The form gained mainstream popularity through serialized web fiction and adaptations into manga and anime. Notable works include That Time I Got Reincarnated as a Slime, Re:Zero − Starting Life in Another World, and Sword Art Online, though the latter blends virtual-world concepts with isekai through its premise of a game becoming real.

Themes and variations

Isekai stories often explore adaptation and power dynamics: the protagonist learns a new language, culture, and political landscape; many narratives feature RPG-like mechanics such as levels, classes, skill trees, and quests. Subgenres include reincarnation tales (the protagonist is reborn as a new person in the new world); transportation or summoning tales (drawn into the world by magic or accident); and reverse isekai (characters from another world arriving in the protagonist's world). Common tropes include overpowered protagonists, political intrigues, dungeon battles, and collaboration with native factions or creatures.