Akira Yagami, an ordinary and altruistic office worker, dies after pushing a child out of the path of an oncoming truck. Instead of a peaceful afterlife, he awakens in a fantastical world, but not as a powerful hero or a noble mage. He has been reincarnated as a goblin, one of the weakest and most despised monster species, which most humans consider little more than a nuisance to be exterminated.

Akira quickly learns that the life of a common goblin is brutally short, with a natural lifespan of only about seven days. The other goblins in his new tribe live and die in the blink of an eye, passing on their skills to each other in a desperate cycle of survival. However, due to the regrets of his untimely death in his former life, Akira is granted a unique skill called "Human 80 Years," which blesses him with a full human lifespan. This singular advantage gives him the precious resource his kin lack: time.

Using his longevity, Akira begins to thrive where other goblins perish. He starts inheriting the skills of the short-lived goblins around him, slowly accumulating a vast arsenal of abilities. His journey from a lowly monster to a true power in the world truly begins when he encounters the dying Demon Lord. On the verge of death, the Demon Lord passes on a unique and powerful skill to Akira: "Law of the Jungle," an ability that forces any monster he defeats to obey him absolutely. This transforms him from a mere survivor into a potential leader.

As Akira's power grows, he establishes himself as the mayor of a goblin village, using his past life's corporate management skills to shape his own society. He attracts a diverse group of companions. These include Karen, a human knight serving as a security inspector who initially pursues his goblin kind but later becomes a crucial ally, and Chloe, a mysterious demon girl. The series follows Akira as he navigates a world that fears and hates him, builds a community from nothing, and confronts a new, unknown threat that rises to fill the power vacuum left by the late Demon Lord.

Several notable narrative arcs shape the series. The initial arc focuses on Akira's survival and discovery of his skill inheritance ability, establishing the mechanics of his growth. A major turning point is the inheritance of the Demon Lord's power, which elevates Akira from a village leader to a potential contender for the title of the strongest being in the world. Later storylines explore the political complexities of his existence, such as when a goblin from his village is attacked in a human city and Akira finds that even allied nobles have no legal authority to punish crimes against monsters, forcing him to seek justice through other means. These events drive the central conflict of a being who must carve out a place for himself and his people in a world that refuses to acknowledge their right to exist.