From Tokyopop:

Hack//4 Koma" is a four-panel (a.k.a. Yonkoma) manga series set in the popular multimedia world of .Hack. Most of the 4 Koma are filled with gags and parodies centering mostly around the main characters of the first (Kite, BlackRose, Helba, etc) and second (Haseo, Atoli, etc) series of ".Hack" videogame