".hack//Liminality" is a four-episode OVA series set in the same universe as the ".hack" franchise, focusing on the real-world consequences of events occurring within the virtual MMORPG "The World." The narrative unfolds concurrently with the events of the ".hack//Infection" video game series, exploring the impact of the game's anomalies on the physical world. The story centers on Mai Minase, a high school student and accomplished violinist, who becomes entangled in a mysterious incident after receiving a package containing a beta version of "The World." Upon playing the game, she experiences a sudden blackout and awakens in a hospital, where she learns that similar incidents have caused comas in other players.

Mai's investigation into the phenomenon leads her to Yuki Aihara, a university student and former beta tester of "The World," who has been researching the game's connection to real-world events. Together, they uncover the involvement of a powerful corporation, CC Corp, which developed "The World." The corporation's experiments with artificial intelligence and virtual reality have inadvertently created a dangerous link between the game and reality, causing players to fall into comas when their consciousness becomes trapped in the game.

As the story progresses, Mai and Yuki are joined by Tomonari Kasumi, a journalist investigating CC Corp, and Junichiro Tokuoka, a scientist working on the game's technology. The group discovers that the comas are caused by a program within "The World" called "Pluto's Kiss," which disrupts the brainwaves of players. The narrative delves into the ethical implications of virtual reality technology and the consequences of blurring the boundaries between the digital and physical worlds. The series concludes with the group working to prevent further harm, though the long-term resolution of the crisis remains tied to the broader events of the ".hack" franchise.

The characters are grounded in their real-world struggles, with Mai grappling with her identity and future, Yuki confronting her guilt over her involvement in the beta testing, and Tomonari seeking redemption for his past mistakes. The series balances its exploration of technological themes with personal growth and interpersonal dynamics, offering a thought-provoking addition to the ".hack" universe.