Nirvasyl Syndrome is a condition that affects beastmen, turning them into a monstrous and more savage version of themselves.
The name comes from an ancient Eastern European city called Nirvasyl, where the condition first occurred a thousand years ago. Fueled by extreme stress that overload and corrupt their beast factor, a beastman undergoes an out-of-control metamorphosis in which they assume a more monstrous form. Fueled by rage and hate, the affected beastman lose all sense of self and attack everyone and everything on sight. To add the threat they pose, the affected beastman can mutate to develop more destructive abilities in addition of increased physical power and durability. For example, Hiromu Yaba develops an additional pair of smaller arms and later, sharp spikes around his body.
The actual cure for this syndrome is human blood, particularly ones that turned into a human-turned beastman such as Michiru's. However, Alan plans to revert the beastmen back into humans with Beast Factor Termination Vaccine and cause every single beastmen in Anima City to go berserk as part of his scheme to cleanse his kind of half-breeds.