Sword Art Online Re:Aincrad, Vol. 2 (manga)

Die in the game, and you die in real life. This is Sword Art Online, the latest VRMMORPG, and Kirito now finds himself trapped in its unforgiving virtual world. By chance, he comes across a swordswoman named Asuna, who agrees to team up with him to challenge the boss of the first floor. The two join a large raid party to take down the beast, but when its attack patterns become unpredictable, the group's resolve will be tested...