Chi Su Mu enjoys feeding homeless dogs and completing household chores, but his life takes an unexpected turn when he develops "Kleine-Levin syndrome" and meets the fiery "fox" named Gu Xue. Despite his kind nature, Sumu becomes an unintended member of "Whale Fall" and is compelled to participate in a vaccine heist masterminded by Gu Xue. Despite having no experience in combat, Sumu is transformed into a skilled agent under Gu Xue's guidance. Joining the organization teaches Sumu the duties and goals of being a "sentinel and guide." While initially admiring Gu Xue's personality, Sumu eventually develops mutual romantic feelings for him.
