Two months into their imprisonment in the death game Sword Art Online, Kirito and Asuna push into the game world Aincrad's fifth floor, a ruin-choked maze crawling with undead monsters and player-killers alike. Kirito's beta-tester knowledge keeps them a step ahead of the traps, but it also paints a target on his back, and Asuna starts to chafe against how much she's leaning on him to survive. This manga adapts the Sword Art Online: Progressive light novels, continuing after Houei no Barcarolle and preceding Ougonritsu no Canon.