Shouta Aikawa is an energetic third grader who is fond of insects. He lovingly raises a rhinoceros beetle larva for two months, naming it Moriking. However, instead of transforming into a beetle at the end of its larval stage, Moriking overcomes the wall of evolution and evolves into a human being! Furthermore, Shouta's beetle pet is in fact an insect king, born every hundred million years. As part of Moriking's trial to become the king of all insects, he must venture out into the wider world and survive. In doing so, he quickly recognizes Shouta as his savior and owner, and wishes to remain with the Aikawa family.

Although Shouta has no qualms about accepting a humanoid beetle who can fly and walk on walls, his high school sister Shouko does. Somehow persuaded by Shouta's pleas, Shouko and their parents ultimately decide to accept the insect king into their family. But a huge challenge lies ahead for the owners of this young and attractive beetle: they must help Moriking defeat the other four competing candidate kings to become the lord of the forest, who rules over all the insects in the world.

Volume 2: Shinrin Shugosha Moriking