The narrative begins in the aftermath of a fierce battle, where the protagonist, a Necromancer, lies among the dead. He had planned to resurrect himself as a Lich using a forbidden spell, but the Hero's party, upon discovering his body, decide to leave him behind, deeming him "creepy" and an inconvenience. Awakened by rats, the Necromancer completes his transformation into a Lich, a skeletal being. He is then approached by Alice, a Ghost and one of the Demon King's Six General, who mistakes him for a powerful Lich who once served the Demon King.
Despite his human heart, the Lich finds himself drawn to the allure of research, believing it to be more important than humanity's fate. He decides to side with the demons, and Alice escorts him to the "Lich Laboratory," a modern facility filled with his research materials and equipment. The Lich expresses his desire to keep his revival a secret from both humans and the Demon King, prioritizing his research above all else. He believes that by advancing his studies, he can contribute more to the world than through war.
The Lich, now calling himself "Ske-Lich" to maintain his disguise, requires materials for his research, specifically the fur of Beastmen. Alice explains that obtaining them requires advancing the front lines against humans, as Beastmen reside in human territory. Ske-Lich agrees to lead an offensive, disguised as a skeleton, to secure a stable supply of Beastmen. He demonstrates his mastery of necromancy by single-handedly defeating a human army led by the "Undead Slayer" Saintess Rosalie, whose holy magic is rendered ineffective by his advanced undead manipulation and regeneration abilities.
Following this victory, Ske-Lich and his undead forces occupy a Beastman village, but the rampaging undead slaughter the inhabitants and burn the village. Ske-Lich, realizing his research materials are now dead, uses his necromancy to revive the Beastmen, albeit with a pragmatic approach, viewing them as experimental subjects for his "secret medicine" creation. He negotiates with the revived Beastmen, offering them a comfortable life in exchange for their cooperation, emphasizing that their lives are a resource.
The narrative then shifts to Ske-Lich's need for funding for his research. He visits the Demon King, who, surprisingly, is a young girl who knew him before his transformation. She reveals that she is the "real" boss, and he is the "underboss," and provides him with a key to a treasure vault containing his accumulated wealth from past medical ventures.
Ske-Lich decides to take on disciples to help with his research. He chooses young Beastmen, believing their minds are more receptive to learning necromancy. He encounters resistance from a red-haired Beastman girl who views necromancy as blasphemous, but Ske-Lich coldly dismisses her religious objections, emphasizing the practical value of life as a resource. He eventually convinces the children to learn necromancy by framing it as a way to bring happiness.
Later, Ske-Lich intervenes in a conflict between rampaging Giants and Beastmen, demonstrating his power by effortlessly killing and reviving a Giant. He is then approached by Inge, a proxy for the Six General of the Giants, who requests his aid in defeating the "Giant Slayer" warrior Leila, who stole their general's sword. Ske-Lich agrees, not for revenge, but for the deceased general's corpse, which he intends to use for his research. He then confronts Leila, using the revived Giant General as a weapon. The battle is fierce, with Leila's powerful attacks being countered by Ske-Lich's undead regeneration and manipulation.
