Underworld runs on FLA (Fluctlight Acceleration) rates. Initially, 1,000x real time. But by War of Underworld , the link between real-world seconds and Underworld years becomes a plot weapon. The climax relies on exploiting this time link: while 20 minutes pass in reality, months of war unfold inside.

For the most up-to-date information, note that Alicization Lycoris is no longer the newest "Link." In 2023, Bandai Namco released .

The tragedy lies in the fact that to save the Underworld, the link to the real world must eventually be severed or heavily regulated, isolating the created civilization.

Represents the link between human memory and digital existence.

The central conflict arises when the link between the Ocean Turtle and the external internet is hijacked. This "link" serves as the gateway for the antagonists (the American mercenary group "Critter") to inject players from the MMOs Gun Gale Online and ALfheim Online into the Underworld, turning a closed simulation into a chaotic battlefield.