#18 TO THE WORLD TREE

Lyfa leads Kirito to the World Tree, which stands in the center of Alfheim.
But when they try to depart Sylvain, a member of Lyfa's party, Sigurd, stands in their way. Because she's annoyed by the way he belittles Kirito, and by the way he tries to constrain her, Lyfa announces that Kirito is her new partner.
Meanwhile, trapped at the top of the World Tree, Asuna, not knowing whether Kirito is dead or alive, is filled with anxiety and fear...