The zookeeper needs to train various animals who turned into humanoid girls called Friends due to the appearance of an abstract crystal emerging from a volcano which also caused the appearance of creatures that can take the shape of various objects called the Ceruleans/Celliens. Those creatures hunt down Friends to feed on them and also work for the Cerulean's queen like an ant tribe. Those crystals allow the animals of the zoo to stay in their new humanoid form and also developing a unique wild skill. Friends are able to talk fluently human language while still having their animal behaviour. Some lives in groups like the Nyan Nyan Family consisting of mainly cat/feline animals who their leader is the Serval.