During the events of the Submerged Fish Hunt test Yu Han Sung warmed the regulars that the Bull is a fearsome unidentified creature that made its appearance in the Wine Glass a few years ago. The Bull possesses an enormous appetite and is a creature that typically wouldn't exist at such a low level of the Tower, which makes its presence at the Second Floor unusual. The creature is incredibly strong and has amazing speed, this he is considered to be the top of the food chain in the Wine Glass. Because of its temper and appetite, it gained the nickname "Bull". It eats both Mangdol Whales and humans. Several Regulars have fallen prey to it already. Sunwoo Nare notes that a capable Anima would be able to control it.
It later revealed that Ren used the Bull in order to eliminate Anak during the Submerged Fish Test. However, when this failed, it was sent to kill Baam. After being frozen several times by Baam, it was blasted through the mouth and fell to the bottom of the Wine Glass, where it presumably died.