Sword Art Online: Progressive - Kuraki Yuuyami no Scherzo

Third installment of the manga adaptation from the light novel series of the same name drawn by Puyocha.
Nearly two months have passed since Kirito and Asuna found themselves trapped in the world of Aincrad. Now, they're making their way through the ruins-themed fifth floor, where all sorts of undead monsters—and player-killers—lurk in the shadows!
(Source: Yen Press)
Note: Includes 1 extra chapter.