Terra is a planet where humans and beasts live together in peace. After the arrival of strange visitors from another world, the beasts start attacking humans at will. The common perception is that the strange visitors are to blame for the sudden change. How true this perception is, of course, unknown.

Dilo is a young man who lives in forest with beasts that are have not been affected by whatever is happening. He starts his adventure to solve that mystery. On his journey, he'll meet many people from the other world. Some will assist Dilo, while others profit from the chaos on Terra, and inevitably get in his way.