Sword Art Online Light Novel Volume 04

Prologue
Looking high above you see the land and then the sky from the underworld Joutunheimr.

Chapter 5
Sylph warrior Lyfa, the game persona of Suguha, and the Spriggan race Kirito has trespassed into the underground world: «Jötunheimr». While hiding in a shrine, they witness a battle between two evil-Gods; a human shape giant with three faces against an elephant-headed jellyfish giant. Feeling sympatric for the giant jellyfish, they provided support and provoke the human giant into following them into a trap, allowing the giant jellyfish to finish it off when both the giants fell into the icy water. Appreciating their help, the giant jellyfish, who they later call Tonkii, became their companion and vessel to travel the icy land of «Jötunheimr».

After avoiding the other evil-Gods, Tonkii took a rest when they reach the roots of the World Tree. As Suguha and Kirito were sightseeing, they were interrupted by the presence by an evil-god hunting party of 24 elite Undine players. As their friend: Tonkii was in trouble, Suguha and Kirito intervene to protect him. During the conflict, Tonkii evolves and suddenly sprout his wings to fly, he soon rain down monstrous attacks and fight off the elite Undine players to near annihilation.

Ready to continue the journey, Suguha and Kirito once again rode on Tonkii, and along their way, they discover the sealed whereabouts of the strongest legendary sword: «Holy Sword Excaliber». Decided to try to capture it in another time, Tonkii finally brought them back upper land, and flew off to meet again at another time. Suguha and Kirito finally reach the beautiful, majestic city known as «Aarun». After the long eventful night, they finally can log out of the game to rest.