The Fourth Unit is lead by the Fourth Commander, Lore, and all members of the Unit answer to him, or to his disciple, Ghost. They act together during crisis, combat, training, and so on. Members of the Fourth Unit may either volunteer, become chosen by Lore or Ghost, or become assigned to the Unit by the request of Nero, the Leader, or another Commander, although the member may decline the selection or request.
Formerly, the Fourth Unit was lead by Beyral, whom took up the position as the Fourth Commander in the earlier days of the Celestial Heavens. When she no longer thought it was a necessity, she voluntarily stepped down from her role, and the position was handed over to Lore, after he was nominated for it and was offered the role.
Lore is an especially busy individual with a lot of responsibilities, which leaves many of the day to day happenings within the Unit to Ghost. Members of the Fourth Unit are commonly those that have worked closely with Lore in especially difficult assignments previously or are connected to some other member of the Unit. They are most commonly the Unit that deals with especially unusual, alien, or otherworldly assignments.