The narrative begins with Mamiya Yuuto, a 32-year-old salesman, on his way to a business meeting. Dissatisfied with his company's strict dress code in the heat, he walks to his appointment, regretting not driving. Suddenly, a voice calls out, and Yuuto finds himself pulled into a black void, disappearing from view.
He awakens in a surreal, undefined space, met by a calm, young boy with acorn-shaped hair. The boy reveals that Yuuto is not dead but is being transferred to another world, a fantasy realm of swords, magic, and skills, which he describes as popular and desirable. Yuuto, familiar with fantasy novels, asks about "cheats" or special abilities. To his dismay, the boy states Yuuto will be transferred with no special powers. Yuuto, realizing the danger of such a world without any advantage, demands to be returned. The boy, however, implies Yuuto's dissatisfaction with his current life made him a suitable candidate. After Yuuto presses for any advantage, the boy reluctantly agrees to de-age him to 13 years old, which Yuuto accepts, requesting to start from 0 years old, but is advised against it. Yuuto then negotiates for the ability to view a status screen, which the boy provides as a "handmade" feature. Despite Yuuto's protests that this offers no real advantage, he is abruptly sent to the new world.
Yuuto finds himself in a dense forest, realizing his clothes are now comically large due to his de-aging. He discovers he is indeed 13 years old, approximately 140cm tall. His immediate goal is to find a high point to survey his surroundings and locate water, fire, and shelter. He attempts to climb trees using his belt as a makeshift rope, eventually reaching a vantage point. From there, he sees an endless forest, but also a distant mountain range, suggesting civilization might lie in that direction. He also notes the sun's position for direction and discovers his wristwatch has a compass function. He spots a potential river, offering hope for water and a path.
On his second day, Yuuto struggles to sleep in a tree due to discomfort and the sounds of unknown creatures. His goals are to reach the river, gather food, track time, and potentially engage in his first combat. He reflects on his past life, his boss Kasahara, and the skills he might acquire. He encounters a one-horned rabbit, a "Horned Rabbit," which he identifies as a monster. Using his suit jacket as a makeshift lure and his tie to constrict it, he manages to defeat the creature, a victory that feels like a significant struggle.
On the third day, Yuuto successfully defeats another Horned Rabbit and discovers a green fruit that is edible and hydrating. He also learns that skills can be gained through actions, as his "Gathering" skill increases after picking fruit and his "Physical Training" skill increases after subduing the Horned Rabbit. He confirms the world's day cycle is similar to Earth's and that his solar-powered watch is a valuable tool. He realizes that approaching water sources increases the likelihood of encountering monsters.
On the fourth day, Yuuto encounters goblins. He develops a routine of using his flashlight to disorient them and his screwdriver to defeat them. He also encounters a mole-like creature that uses magic, forcing him to defend himself with his briefcase and eventually defeat it with a kick, leveling up and gaining the "Charge" skill. He learns that skills can be gained from monsters and that his status screen provides detailed information. He finds a cave to use as a temporary shelter and begins to strategize about his growth, noting the potential for diverse skill acquisition.
Yuuto continues his journey, encountering and defeating more monsters. He learns that his "Charge" skill allows for rapid, direct movement. He also discovers that certain monsters possess skills, and defeating them grants skill experience. He finds a more comfortable shelter near a river and begins to analyze his stats and skills in detail. He realizes that skills can be acquired through various actions and even thoughts, and that acquiring skills can grant stat bonuses. He reflects on his past gaming experiences and the potential for character customization in this new world.
Yuuto's journey continues as he encounters and defeats more monsters, refining his combat strategies. He learns to use his skills effectively, including "Charge" and his tools, to overcome his opponents. He also discovers that the environment plays a role in skill acquisition, with actions like fishing and climbing contributing to skill growth. He finds a cave that serves as a safe haven and continues to analyze his progress, noting the potential for further skill development and stat increases. He begins to feel a sense of purpose and excitement in his new life, reminiscent of his past gaming endeavors.
Yuuto's progress is interrupted when he hears human cries for help. He rushes to investigate, encountering two boys and a girl being attacked by three goblins, one of whom wields a sword. Despite his self-imposed rule of fleeing from multiple opponents, Yuuto decides to intervene, recognizing the children's vulnerability. He uses his skills and tools to fight the goblins, coordinating with the knife-wielding boy, and manages to defeat two of them. He reflects on the importance of decisive action and the need to acquire more power.
