The protagonist, a nameless mercenary who died in battle, awakens to find himself reincarnated as a kobold, a small, dog-like monster. Initially disoriented by his new form and inability to speak human languages, he quickly adapts to his surroundings. He lives in a dark cave in a forest with his kobold family, consisting of his mother, father, sister, and brother. He observes the short lifespan of kobolds, averaging only ten years, and the primitive, survival-focused lifestyle of his kind. Driven by a desire to avoid a meaningless death and fueled by the regret of his past life, he resolves to become stronger. He begins rigorous training, encouraging his siblings to join him. While his sister participates enthusiastically, his brother quickly loses interest.
As the young kobolds grow, they venture further from their settlement. During one such outing, a fearsome Gray Bear attacks their group. The protagonist warns his companions, and they attempt to escape by climbing trees. However, his brother falters and is tragically killed by the bear. The protagonist, along with his sister and other young kobolds, manages to escape back to their settlement, but the loss of life weighs heavily on the community. This event solidifies the protagonist's resolve to train the surviving young kobolds forcefully, instilling in them the importance of strength through the painful memory of their fallen comrade.
Over time, the protagonist and his sister, now known as Dagger, along with other trained kobolds, become formidable. They acquire better equipment by ambushing and disarming adventurers, a necessary measure for survival and to prepare for future threats, particularly the Gray Bear that killed their brother. The protagonist, now calling himself Archer, leads his companions, including Buster (a large, strong kobold), Dagger, and others, in honing their combat skills with their new weapons and armor. They establish a hierarchy within the settlement, with Archer at the top.
Their journey takes a dangerous turn when they venture into the "Balbera Forest," a perilous area known for powerful monsters. They encounter a formidable Rock Lizard, a creature far stronger than typical monsters in the region. During the intense battle, Buster is injured, and Dagger sprains her leg. Archer unleashes a roar that enhances his companions' abilities, and Buster, with a surge of power, manages to sever the Rock Lizard's horn. Archer then uses his newly discovered earth and wind magic to immobilize the creature, allowing Dagger to deliver the finishing blow with the Rock Lizard's horn.
Following the battle, both Archer and Dagger undergo significant transformations. Archer evolves into a High Kobold with enhanced physical abilities and rudimentary magic, while Dagger transforms into a Kobold-Foxy, resembling a fox-like kobold with increased agility and illusionary magic. Buster also evolves into a Kobold Warrior. As they assess their injuries and the valuable horn, they are approached by Muriel Vest, a young human mage and biologist who was fleeing the Rock Lizard. Despite their initial apprehension and the language barrier, Archer's past life as a human and his inherent empathy lead him to approach Muriel, recognizing her injured state and offering assistance with his healing magic, a skill he discovered he possessed.
