Infinite Dendrogram (Manga) Volume 2 by Sakon Kaidou

The trouble with full-on MMO's is that there's always some overpowered nutcases who can show up and wreck things. It seems like Infinite Dendrogram is no different, with a set of four in the Kingdom of Altar alone! Having previously been PK'ed out of the game, Ray continues his quest to level up and press ahead, But in the background, political maneuverings cause the game's top players to make their presence known.