The protagonist, Shuya, finds himself in a stark white space after being pulled through a dimensional rift. He discovers a desk and chair, and after a brief reality check, he realizes he's not dreaming. A floating text prompts him to choose between "Yes" or "No" for reincarnation into a different world. This new world is described as one with gods, multidimensional travel, and various beings, including other transmigrators and reincarnators. After considering his bleak life on Earth, Shuya chooses "Yes."
He then undergoes a character creation process. He selects the "Vampire Half" race, drawn to its unique abilities and fewer weaknesses compared to a full Vampire. He then chooses four extra skills: "Translation Instantaneous" for communication, "Mark of Light" to counter his light-based weaknesses, "Chain Factor" for a versatile weapon, and "Brain-Spinal Cord Revolution" to enhance his physical and mental capabilities. His race evolves into "Light Magic Seivalt," gaining new abilities and resistances.
Shuya's character creation is interrupted by a monstrous white entity with multiple arms and a gas mask, which attacks him, inflicting severe injuries and disabling some of his skills with a paralyzing poison. Despite his weakened state and the loss of his "Brain-Spinal Cord Revolution" skill, Shuya's innate vampiric abilities begin to manifest, including rapid healing and a surge of power. He is forced to flee from the monster, eventually falling into a massive bone pit.
In the bone pit, Shuya discovers his enhanced physical abilities allow him to survive the fall and even gain new skills like "Throwing" and "Stealth" through his actions. He equips himself with scavenged items and begins to navigate the treacherous underground world. He encounters a dwarf named Roa, a banished member of the Langur Empire, who explains the underground world, its dangers like the "Granba" monsters, and the existence of human settlements like the underground cities. Roa, initially wary of Shuya as a "maggle" (surface dweller), eventually shares information about "divine tool stands" that might lead to the surface, though he warns they are likely broken and inaccessible. Roa departs, leaving Shuya alone once more.
Shuya continues his journey through the underground, encountering various monsters like slugs and wolf-like creatures with split mouths, which he defeats using his newfound skills and weapons. He also discovers glowing moss that provides sustenance and water. His journey leads him through ancient ruins and a labyrinthine cave system. He learns more about his abilities, particularly his "Chain" skill, which he uses to navigate and fight. He also experiences the effects of his "Blood Plasma Deficiency" and the potential for "mummification" if he doesn't consume blood, realizing his vampiric nature requires it.
His travels eventually lead him to a vast underground cavern filled with bones and illuminated by strange lights. He encounters a group of goblins, whom he defeats using his skills, gaining the "Stealth" skill in the process. He explores a ruined library and continues his journey, eventually finding a massive circular structure described as a "gate" or "ring" by the inscription "Zaralap, Near and Far." He avoids entering it due to a bad premonition.
He continues his journey, encountering the same white monster that attacked him earlier. This time, the monster reveals it has a skill that inhibits his own, preventing him from using "Brain-Spinal Cord Revolution." Shuya's condition worsens, with his blood plasma deficiency reaching critical levels and his body succumbing to the poison. However, a surge of power, possibly from his "Bloodline of the True Ancestor" skill, triggers a transformation, unlocking new abilities and a new race: "Light Magic Seivalt." This transformation seems to counteract the poison and grant him greater control over light and dark magic. He is then forced to flee from the monster again, escaping into a new area.
