Set in the Dark Forest Biological Research Institute, the story follows Damen, a breeder bound by a blood pact with Lucas, a three-tailed fox mountain god who once saved his life. Manipulated by the cruel institute boss Kael, Damen is tricked into believing foxes killed his father. He cruelly cuts off Lucas’s three tails on his forced wedding day, unaware Lucas carries their unborn cubs. Wracked with pain and hatred, Lucas evolves into a nine-tailed fox after being separated from his newborn kits. Later, Damen uncovers Kael’s lies—his father died shielding Lucas’s mother decades ago. Tied by an unbreakable life-sharing blood bond, the two endure torture, betrayal and separation, united to defeat Kael. After a deadly battle, Lucas sacrifices his vitality to revive fatally wounded Damen. Three years later, they live peacefully in a mountain cabin with their two kits, welcoming another new life, healing all past trauma together.
