Beast Factor

Beast Factor (獣因子) is a genetic component that allows beastmen to transform into their beastman forms in BNA: Brand New Animal.

Description
In addition of endowing a beastmen their animal form, Beast Factor also endows them with superhuman abilities related to their animal form in question. For example, bird beastmen possess wings and talons for flight and grabbing things respectively like birds and rhino beastmen possess enhanced strength and durability in addition of horn to damage enemies with.

The extent of a beastman's shapeshifting ability seems to relative with how they possess this genetic component. Whereas regular beastmen mostly limited to a single anthropomorphic animal form (with notable exception of Shirou who exposed to souls and blood of his fellow beastmen inhabitants of Nirvasyl that resulted his "transcendence" into the original Ginrou), those who received beast factor through artificial means like Nazuna Hiwatashi and Michiru Kagemori can freely assume any animal form they wish, including a full animal form. As beast factor's condition is relative to the bearer's emotions, he/she must not succumb to stress to prevent it from consuming them, a condition that referred as Nirvasyl Syndrome.