Sword Art Online is a Japanese light novel series written by Reki Kawahara, which follows the story of players trapped in virtual reality MMORPGs. The series begins with the release of a new VR game called Sword Art Online (SAO), where thousands of players, including protagonist Kirito, are unexpectedly trapped in the game by its creator, Akihiko Kayaba. The players soon discover that if they die in the game, they also die in real life. Kirito, a former beta tester, embarks on a quest to clear the game's levels and escape, forging relationships with other players, including Asuna, who becomes his partner and love interest. As the story progresses, Kirito faces new challenges in different virtual worlds, tackling various threats that emerge from both in-game and real-life forces.

The narrative expands into multiple arcs, with Kirito and his allies diving into other virtual worlds, such as ALfheim Online and Gun Gale Online, and encountering increasingly complex threats, including malicious players, AI entities, and global conspiracies. Sword Art Online explores themes of survival, identity, and the nature of reality as characters struggle to balance their lives within virtual worlds with the challenges of the real one. Over time, Kirito’s journey intertwines with the lives of others, including Asuna, Leafa, Sinon, and many others, forming deep bonds and working together to confront the sinister forces that endanger both the virtual and real worlds. The series has since expanded into manga, anime adaptations, and video games, gaining a global fanbase. In addition to its successful anime and light novel adaptations, Sword Art Online has inspired a wide range of merchandise, including action figures, plush toys, posters, and clothing, as well as video games and collectible items such as keychains, statues, and limited-edition gifts, allowing fans to immerse themselves further into the world of SAO.