The Underworld
RATH's artificial world, where time runs a thousand times faster than outside.
The Underworld is the virtual world of the Alicization arc. RATH, a research body under the Ministry of Defense, built it with The Seed package to raise an artificial intelligence, and Kazuto was recruited to test the Soul Translator, the far more realistic full-dive machine used to enter it.
Lore & Background
Inside the Underworld time moves a thousand times faster than in the real world, and Kirito's memories of what happens there are restricted. After Johnny Black mortally wounds Kazuto with suxamethonium chloride, RATH recovers him and he is placed inside long-term. There he grows up with Eugeo and Alice in Rulid Village, and his fight against the Axiom Church, its Integrity Knights and the Administrator Quinella follows.
More in Worlds & Locations
Elsewhere in Sword Art Online
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced