Sword Art Online: Alicization

The Soul Translator is a cutting‑edge full‑dive system that engages with the user's Fluctlight—the digital counterpart of a human soul—and fundamentally departs from conventional brain‑signal transmission, with a sophisticated neural interface. Private research firm Rath seeks to refine its invention by recruiting Sword Art Online veteran Kazuto Kirigaya to enhance its precision. He serves as a part‑time tester, evaluating the system"s performance within the Underworld—the surreal domain produced by the Soul Translator—and ensuring safety. Under the confidentiality agreement, all memories formed inside the virtual realm are erased when one re‑enters reality strictly. Kazuto only vaguely remembers one name—Alice—which induces discomfort whenever it surfaces in the real world deeply. While escorting Asuna Yuuki home one night, Kazuto encounters a known adversary. He sustains fatal injuries during the clash and collapses. Upon regaining consciousness, he realizes he has plunged fully into the Underworld with no apparent exit and is haunted by the echo of that name. Determined to return, he embarks on a perilous journey to find a path back to the physical realm. His quest will test his resolve.