This class is the easiest to catch and the easiest to keep. This class is not aggressive, they just have different looks and behavior, but remember, even if this class is in S, it can be dangerous to approach them.

This class is easy to catch and keep, their appearance and movements are different and they are aggressive, dangerous to approach, they need to be watched from a distance.

Class D is the class that is difficult to catch and hold, they are extremely aggressive and do not approach them at all.

This class is extremely difficult to catch, and even if they hide, they constantly try to escape. When such creatures are caught, they are imprisoned in a well-protected place.

This class includes creatures brought to the facility for the first time. It is not recommended to approach creatures in this class. This grade level only lasts for about 5 months and then a class change becomes mandatory and scientists make this class change and determine which class some people should move to.

note: if scientists were transferred to the wrong class, which caused the scientist to die

Creatures of this type cannot be caught, or even if they are caught, they do not stay in place in the facility. It is very difficult, they attempt to escape every second, and creatures of this type kill 1000 people a day, so creatures of this type must be well protected or destroyed.