Sword Art Online: Progressive - Nether Twilight of Scherzo summary:
Kirito and Asuna have been trapped in the death game Sword Art Online for less than two months. The two had reached the fifth floor, which is themed around ruins. Adventuring through catacomb dungeons and huge mazes, there are ghost-type monsters, which Asuna cannot handle, as well as Player Killers who are showing suspicious movement. (Source: Kadokawa, translated)