In The Games
 Mega Man Battle Network 3
BeastMan is the Navi of Takeo Inukai, the zookeeper of the Yoka Zoo. Inukai plants chips in all of the zoo animals that allow him to control them, and when Lan and MegaMan visit Yoka, he makes them escape their cages and wreak havoc throughout the zoo.
Lan then sends MegaMan into the Zoo's computer network and finds his way to the control system at the end. He does this by gathering Mr. Progs who represent different animals and using them to destroy Mettaur viruses that represent other animals. When he reaches the end, he encounters BeastMan, who immediately hates MegaMan because of his humanoid appearance. MegaMan then fights and deletes him.
BeastMan's alpha version can be encountered at a dead end in SciLab 1. Unlike most other Navis whose beta versions appear in the same general area as their alpha version, BeastMan's beta version appears in Lan's dog house next to his house.