Sword Art Online Progressive Scherzo of Deep Night, Vol. 1 (manga)

Nearly two months have passed since Kirito and Asuna found themselves trapped in the world of Aincrad. Kirito’s experience with the beta version of the game has put him far ahead of the curve, but it has also attracted the attention of some dangerous players. For Asuna, his competence has been a godsend in this harsh world, yet she can’t help but feel like her overreliance on Kirito’s skills is becoming an obstacle to their growing relationship. Even so, they’ll have to work together to make it through the ancient ruins of the fifth floor, where all sorts of undead monsters and player-killers lurk in the shadows!