When there was nothing but nature, humans and animals, a great darkness plagued the lands almost consuming everything in its way. Inside this mass of darkness dwells the monsters that were once trapped by a powerful sorceror who sacrificed all his power to send the monsters into another dimensional world. The humans had to fight for survival but the monster's power grew much stronger than before and forced the humans to take full defense and withstand every damage the monsters could give.
After 4 months from the monster incident, the humans became brutal to the animals as they are the only food source left and are helpful in some tasks need but the gods were angry by this behaviour and transformed all animals into Animan, taking the body shape of humans while still having every aspect of its former animal self, then they tortured back at the humans until they had enough.The Animan have noticed how oddly weak the humans have now become and decided to take the front battle lines and fight the monsters in the humans place to save them from extinction.
During the battle for life, a stronger force which feels like the source of the chaos has caused a sudden break of the world to multiple rifts in time and space. The once knowned world of the humans has transformed and divided into multiple different worlds each having some odd unique environment from the others. All humans, Animan, monsters and habitat has been divided but nothing has much change in the war. After some time, a lacrima from the dividing was placed at the edge of the worlds which helps provide the transportation to the other worlds and only the Animan are able to use such a helpful way.
The power of the Animan is unrivaled with the humans as they have a strange power they possess to change into new armor and weapons called classes, which allows them to wield different weapons and allow multiple strategies for them to use in battle. While the Animan deal with the monsters, the humans help support them by strengthening the base they all stay in, creating new and stronger weaponry, provide some information they gathered, and to give out a big meal for a great success from defeating some monsters.
With this new found power, peace shall be attained once again and who knows what new foes awaits for these new heroes of justice...