Eighteen-year-old Azren Vael is the weakest member of a famous Hero Party, gifted only with healing, buffs, debuffs, and tracking. Betrayed on the 80th floor of the Labyrinth of Eternity and left to die against an SS-Rank monster, he accepts an ancient voice’s offer of power in exchange for protecting the races humanity rejected. Reborn as a Z-Rank being with infinite growth, Azren claims the Eternal Heart, discovers the twin swords Noctis and Lumina, and rescues the Elven Princess Elowyn Aurelith. Together they clear all 100 floors, fall in love, and escape into the Demihuman Lands. As Azren gathers Nyx, Queen Dravena, and Vespera, he begins building Elysar, a nation where humans, elves, demihumans, dragons, vampires, and other races can live together. But Noctis urges revenge against the Hero Party and humanity, while Lumina calls him toward peace. With the Demon Lord awakening, Azren must face a power older and more dangerous than the coming threat.