Uru of the Nine Prison is a powerful Full Raid level monster that appears in the quest The Nine Prisons of Heroes and in the Abyssal Shaft Dungeon. Shiroe considers Uru the stongest raid boss in these zones and believes that the Silver Sword couldn´t defeat it in battle.
Gold of the Kunie arc
Shiroe enters in the final room in the Abyssal Shaft where he faces Kinjo and Uru of the Nine Prison, whose power was stronger than the other raid bosses. However Shiroe realizes that Kinjo is afraid, due the attack of the Adventurers being similar a zombie attack, such that they won't back down no matter how many times they die.
Shiroe successfully negotiates with Kinjo and temporarily gains access to the gold he needs in order to buy all the important structures and open fields in the Yamato server and give it all back to the server so that no individual could now hold them, relieving the Round Table Alliance of the duty of maintaining the Guild Meeting Hall. However, he specifically leaves personal property out of the equation so that he wouldn't infringe on anybody else.
With that the Abyssal Shaft Raid Party successfully cleared the raid without the necessity of defeating Uru.