The story picks up after the hero party, consisting of the hero Eric, the warrior Goran, and the mage Rack (the narrator), has successfully driven the Demon King to another dimension after a fierce battle. Though unable to deliver a finishing blow, they left him severely wounded. As the weary party begins their journey home through the dimensional rift, they are ambushed by an overwhelming horde of hundreds of demons. Realizing their depleted state, Rack sacrifices himself, urging Eric and Goran to escape while he holds off the demon army. He uses his magic, including binding spells and a powerful magic bullet, to fight them, but his magic and stamina are quickly drained.
A turning point occurs when Rack is hit by a high-level demon's "Drain Touch," a magic that absorbs energy. Rack, possessing the ability to learn magic, immediately understands its principles and uses it to heal himself and recover his strength. He continues fighting, his power growing rapidly in the mana-rich dimensional rift. To combat his fatigue, he casts a "Marionette" spell on himself, allowing his body to fight even while he sleeps. He fights for an indeterminate, extended period, eventually wielding a stolen demon sword, which he names "Drain Sword," that absorbs life force.
His prolonged battle is interrupted by the return of the Demon King, who had recovered much faster than anticipated. The Demon King unleashes a devastating fiery attack, but Rack closes the distance and strikes with the Drain Sword. He then attempts to use Drain Touch on the Demon King, but a magical barrier prevents it. After a fierce sword duel, Rack's Drain Sword shatters. However, he exploits the Demon King's momentary overconfidence, using a fire spell and then Drain Touch, which bypasses the Demon King's depleted magical defenses. Rack endures immense pain as his skin burns and heals, while draining the Demon King's life force until the Demon King is completely annihilated.
After the battle, Rack finds himself in a desolate plain outside the dimensional rift, nearly naked and penniless, having lost his clothes, money bag, and adventurer card. He makes his way to the capital, where he is initially mistaken for a victim of bandits due to his appearance. The guards, sympathetic to his plight, provide him with temporary identification and some worn clothing. He then attempts to visit Goran, only to be turned away by the gatekeeper of Goran's opulent mansion.
While walking through the city, Rack encounters a statue in the central plaza. Upon inquiring, he learns it is a statue of "Hero Rack," who sacrificed himself ten years prior to stop a demon army. Rack realizes this is him, but is bewildered by the statue's handsome and idealized depiction. He deduces that Eric and Goran, believing him dead, erected the statue in his honor. He also discovers that ten years have passed since he entered the dimensional rift, a discrepancy he attributes to his prolonged battle and the potential side effects of his "Marionette" magic.
Rack proceeds to the Adventurer's Guild, where he is met by a tearful Goran, who has become the Grand Master of the Guild. Goran, along with Eric, who is now the King, had been waiting for him. They explain that Rack has been declared dead and honored as a hero. Eric has changed the currency to "Rack" and commissioned the statue. To protect Rack from potential political entanglements due to his newfound status as a "Grand Duke Rack Franzen," they agree to register him as a new adventurer under the alias "Rock," with a hidden true identity and a low F-rank warrior status, while his true S-rank and titles remain concealed.
Rack, now going by Rock, decides to start anew as an adventurer to understand the changes in the world. He accepts a low-paying goblin extermination quest, intending to let his new companions, the mage Ario and the scout Josh, gain experience. However, they soon discover the goblin presence is much larger than anticipated, and they encounter a Goblin Lord. Rack easily defeats the Goblin Lord, revealing his hidden strength. He then learns from a beastkin girl named Shea, a B-rank adventurer, that a more dangerous foe, a Vampire Lord, is lurking deeper within the caves. Shea, whose family has a vendetta against vampires, insists on confronting it, and Rack, despite his superior strength, agrees to assist her, lending her the Demon King's sword while he fights bare-handed.
