An episode that expands on the ending of “Alicization”! After three hundred years of war, the Underworld is finally united. Vector, who came from nowhere, defeated the god of darkness and brought peace to this land. But time passes, and in the snow-white tower of the Central Cathedral of Ronye, Arabelle, promoted to knight-apprentice, hears shocking words from Kirito, the Supreme Swordsman and the chief arbiter of the human world: “Sooner or later, war will break out again.” This book expands on the ending of Alicization and tells about the events after the Great Underworld War!