iD_entity Vol 4

iD_entity Vol 4 by Hee-Joon Son. An Action manga rated Teen, published in English by Tokyopop in 2005.

High schooler Jang-Gun is a master-level mage in the online game Lost Saga. When he renews his character ID, he accidentally picks up a hacked card, and logging in with it creates an impossibly powerful but airheaded character. Soon he and his guildmates are caught up in strange adventures that blur the line between player and program.