Around ten years ago, gates that connected our world to another dimension began to appear, leading to the rise of hunters who would traverse these gates to fight the magic beasts within. Sung Jinwoo, E-Rank hunter, is the weakest of them all.
Jinwoo and his party appear to have cleared a low-level dungeon, when a hidden path to an unfamiliar temple is revealed. There they encounter a set of commandments and a group of monsters that cause them absolute despair.
Jinwoo remains behind in the temple dungeon to save his few surviving party members, and with a swing from the god statue's blade, his life comes to an end—or so it seems, before he wakes up in a hospital bed.
Having entered the instance dungeon located inside the subway, Jinwoo levels up time and time again by fighting waves of magic beasts. As he gradually makes his way forward, he finds a long stairway leading deeper underground.
Jinwoo joins a party led by Hwang Dongsuk to meet the headcount necessary for a C-Rank dungeon. Joined by another temporary hire, Yoo Jinho, the party defeats beasts without much trouble, but Jinwoo has suspicions about the group's lack of a healer.
While the C-Rank dungeon raid by Jinwoo and the others seems to be progressing well, the moment they step into an area covered in mana stones with a sleeping dungeon boss, things take a wrong turn.
As Jinwoo continues his training, he completes a daily quest one day by doing more than the quest requires, and a key that leads to a certain item appears in front of him.
At the D-Rank raid, Jinwoo is reunited with four of the Cartenon Temple survivors. Together, they explore the dungeon with Kang Taeshik and his men. After splitting up, they hear a scream, and then...
Jinwoo survives tragedy once again, but Woo Jinchul warns him that Hwang Dongsoo, an S-Rank hunter, may be after his life. Determined to grow stronger, Jinwoo teams up with Jinho to raid a succession of C-Rank dungeons, but they attract attention...
Out of the blue, a "job-change quest" pops up in Jinwoo's window. Feeling that it may help him get stronger, he enters the gate. Inside, he fights wave after wave of enemies, culminating in a knight who brings back memories of the Cartenon Temple.
Drained from endless battle, Jinwoo sees a phantom of his past self. To overcome his own past as the Weakest Hunter of All Mankind, he struggles to find a way to clear the job-change quest.
After a scheduled meeting with Jinah's teachers, Jinwoo is asked to talk to one of her classmates, Han Song-yi, who is working as a hunter. In an effort to show her the harsh reality of the job, Jinwoo takes her to a raid designated for new hunters of the White Tiger guild.
Having completed his promise to Jinho to clear 19 dungeons, Jinwoo is stronger than he was when he fought the Cerberus. In order to gather the ingredients for the Elixir of Life and save his mother, he once again enters the S-Rank Demon's Castle dungeon.
