Sword Art Online, Vol. 17 (light novel), Paperback/Reki Kawahara

Critter has successfully created a gateway for the masses that has bolstered the forces of the army of darkness by over 50,000 people. But all is not lost! Two new deities of the Underworld will descend to lend their aid to Asuna: The Blazing White Solus and the Earthmother Terraria.