The story begins with Sato Koichi, a 42-year-old salaryman, being informed by his boss, Mr. Suzuki, that he is being offered an early retirement package due to the company's difficult financial situation. This is effectively a layoff, marking the end of Koichi's twenty-year career. Overwhelmed by the thought of his university-aged daughter, Misaki, Koichi accepts the offer, feeling like a failure as a father.
Leaving the office with his belongings, Koichi walks into the rain, feeling despair. Suddenly, a translucent blue window, like a game interface, appears before him, visible only to him. It displays his name, age, and "Occupation: None," along with a "Skills: ???" entry. He realizes this is the "Status" system that appeared three years prior. Desperately hoping for a way out, the question marks in his skill list change to "Skill: Placement Change." This skill allows him to swap the positions of "Monsters," "Traps," and "Treasure Chests" within the same floor, with limited uses. Koichi is initially crestfallen, believing this skill is useless as it offers no combat ability.
Returning home is unbearable, so Koichi seeks refuge in a net cafe. While browsing job sites, a banner ad for "Daily Hire Explorers, Beginners Welcome" catches his eye. This leads him to learn about the "Dungeons" that appeared worldwide three years ago. These dungeons are dangerous places inhabited by monsters, but also contain valuable "Magic Stones" and "Drop Items" that have revolutionized society. Explorers, individuals with "Skills," venture into these dungeons. Koichi, with his seemingly useless "Placement Change" skill, decides to try his luck, seeing it as a last resort before his life fades away. He researches the beginner-friendly "Goblin Forest" dungeon, conveniently located a few train stops away.
Upon entering the "Goblin Forest," Koichi is immediately struck by the oppressive atmosphere and palpable danger, unlike anything depicted on television. He encounters three grotesque goblins. Cornered and facing certain death, he impulsively uses his "Placement Change" skill. He sees the goblins and nearby objects highlighted, including a "Pitfall Trap." He imagines swapping the position of the lead goblin with the pitfall. To his astonishment, the goblin vanishes, replaced by a deep pit. The remaining goblins are confused, allowing Koichi to use his skill again, trapping one goblin with a "Vine Trap" and another in a "Mud Trap." He realizes his skill, far from being useless, is incredibly powerful when combined with observation and strategic thinking. He defeats the remaining goblins, feeling a surge of hope and a sense of purpose.
Koichi then meticulously analyzes his skill's mechanics: it can be used three times per floor, swapped items return to their original positions after a while, and activated traps become inert. He understands that "Placement Change" is not just about swapping but about strategically placing objects. He decides his strategy will be to first map out the floor, identifying all available "pieces" (traps and treasure chests) and then targeting the monsters. He collects the "Magic Stones" dropped by the goblins, earning his first income through his own efforts.
The next day, Koichi returns to the "Goblin Forest" with a renewed sense of purpose. He efficiently maps out the floor's traps, treating them as his "pieces." He discovers a treasure chest protected by multiple dangerous traps. Since he has already used his three skill uses, he realizes he can reset his skill uses by leaving and re-entering the floor. He then discovers his skill has two modes: "Placement Mode," where he unilaterally places an object, and "Swap Mode," which allows him to exchange the positions of two objects. He uses "Swap Mode" to exchange the treasure chest with a harmless slime, safely moving the chest to the entrance. He opens the chest, finding silver coins and healing potions, which he exchanges at the Explorer's Guild for 35,000 yen, far exceeding his previous daily wage. He uses this money to buy a lavish meal for his daughter, Misaki, who is delighted.
Koichi continues his dungeon delving, his financial situation rapidly improving. He reflects on his past life, discarding old job applications as he embraces his new role as an explorer. He finds a new sense of purpose and pride in providing for his daughter.
Two weeks later, Koichi overhears young explorers discussing strange occurrences in the "Goblin Forest," such as traps appearing in safe areas and monsters being defeated by traps they themselves triggered. They speculate about a mysterious solo explorer responsible for these events, referring to them as "God Solo." Koichi realizes with amusement that he is the one they are talking about. Meanwhile, at the Guild, an elite employee named Hikawa Reina notices the unusual activity linked to Koichi's F-rank registration and his exceptional earnings, marking him as a person of interest.
Koichi, now a registered F-rank explorer, continues to efficiently clear dungeons using his strategic "Placement Change" skill, earning significantly more than he did as a salaryman. He feels a renewed sense of dignity and purpose, dedicated to providing for his daughter and protecting their newfound peace.
