Haruto Tanaka, a 24-year-old ex-salaryman, abruptly quit his "black company" and became a "Seeker" (explorer) to earn quick cash, aiming to avoid poverty until he found a new job. Despite the dungeon's reputation as a dirty, tough, and dangerous workplace, Haruto, a pragmatic and often complaining individual, bought a club and shield and ventured into the dungeon.
His initial foray into the first floor, populated by harmless giant pill bugs, quickly turned into a struggle when over a hundred of them blocked the stairs to the second floor. Forced to fight, his club broke, and he was exhausted, earning only a transparent glass orb that vanished upon touch, which he dismissed as a hallucination. He discovered he had gained "Earth Magic" and reached Level 2.
On the second floor, Haruto encountered Horned Rabbits, which pierced his shield. He learned their weakness (a straight charge, eyes closed during jump, easily dodged sideways) and began hunting them. He also experimented with Earth Magic, successfully creating a piercing thorn but suffering extreme fatigue due to low magic power. His income remained meager, leading him to seek the next floor. However, he was met with another overwhelming horde of over a hundred Horned Rabbits, forcing him to retreat.
Undeterred, Haruto returned, using a net to trap most of the rabbits before engaging the escapees. He managed to defeat them, realizing his magic capacity was limited to about two uses before exhaustion. After dispatching the netted rabbits in a grueling process, he again saw and dismissed a vanishing glass orb. He gained the "Trace" skill and reached Level 4.
The third floor introduced acidic Slimes, which quickly degraded his cheap weapons. He discovered expensive acid-resistant alternatives and, while examining a sword, gained the "Trace" skill, though its purpose remained unclear. His attempt to use Trace with Earth Magic to create a weapon resulted in immediate magic depletion and collapse, highlighting the limitations of his new skill. After using neutralizing agents to combat slimes, he reached the fourth floor, only to find another hundred-plus monster horde, this time of Slimes, prompting another retreat. Covered in slime and smelling terrible, he inadvertently caused a commotion on the train, but also gained "Healing Magic" and reached Level 5.
On the fourth floor, Haruto faced Head Bats, slow-moving but sturdy creatures. He found them surprisingly easy to defeat, but another horde of over a hundred blocked the fifth floor. This "death match" left him severely injured, his equipment destroyed. Wishing for healing, his body glowed, and his wounds vanished, but he again suffered magic depletion. He gained "Spatial Awareness" and reached Level 6, attributing his healing to the new skill.
After investing heavily in new, more durable equipment, Haruto descended to the fifth floor. Here, he encountered Snapping Turtles, large, venomous, and powerful, but slow. He learned to exploit their slow neck retraction after a quick strike. Despite their high drop value, their shells were too hard to remove, and the turtles too heavy to carry, making them impractical to hunt. Another horde of over a hundred Snapping Turtles blocked the sixth floor. He spent six arduous hours systematically hunting them. A "dead" turtle bit him, tearing his calf, forcing him to use all his magic for healing, passing out from the effort. He gained "Toughness" and reached Level 7.
On the sixth floor, Haruto faced increased monster density. He quickly found the seventh-floor stairs, which appeared clear, but were a trap. A treasure chest containing a "Bracelet of Agility" triggered a multi-species horde of over a hundred monsters. The bracelet's speed boost helped him survive the intense battle, though he again depleted his magic and saw another vanishing glass orb. He gained "Magic Control" and reached Level 8.
Now on the seventh floor, Haruto learned his Bracelet of Agility was worth two million yen, but decided to keep it. He encountered Jumbo Frogs, large creatures with powerful tongues. Facing another horde of over a hundred frogs blocking the eighth floor, Haruto, growing increasingly ruthless, used gasoline to incinerate them. This act of "cruelty" backfired when the heat caused hundreds of sticky, low-attacking Jumbo Frog larvae to fall from the ceiling, forcing him into another difficult, messy battle that depleted his magic and left him covered in mucus. Larvae parts were unmarketable, adding to his financial woes. He gained "Body Reinforcement" and reached Level 9.
Haruto's journey through these initial floors transformed him from a naive ex-salaryman into a more experienced, if still financially struggling and often exasperated, dungeon explorer. He has acquired a diverse set of skills, upgraded his gear, and learned to adapt to the dungeon's brutal patterns, including its recurring monster hordes and environmental hazards, while the mysterious vanishing glass orbs continue to appear without explanation.
