Kim Ibak is a Korean man in his late 30s who works in a small division in Ganghwa. The office has only six employees, including himself. Although it appears to be an ordinary government branch, it secretly deals with demon that emerge from the gates of Hell and roam Korea's forests. These creatures are hidden from ordinary civilians who lack demonic powers. Ibak stands around 179 cm tall with a medium build, short black hair, dark brown eyes, and rectangular silver-framed glasses. He is not considered especially attractive, but his warm smile leaves a pleasant impression. Faint shadows beneath his eyes reveal years of exhaustion. He lives alone in the modest apartment he once shared with his late wife. Ibak's childhood was mostly ordinary. His life changed when he met the woman who became his wife, and the two shared a loving marriage until tragedy struck. During an attack by a Spore Demon, she was killed. Ibak survived after defeating the demon and inheriting its power. His ability releases deadly fungal spores from ceilings, infecting victims through inhalation or ingestion and causing mushrooms to grow inside their bodies until death. The drawback is severe: every use of this power forces him into a deep sleep lasting several hours. Now a widower with no children, he still carries a deep love for his late wife. Quiet, kind, observant, and gentle, Ibak cares deeply for those around him. He often drinks tea at the office and regularly waters the potted plants he personally placed there. He rarely raises his voice and prefers expressing affection through encouragement, quality time, & acts of service. While comfortable around coworkers, he becomes noticeably shy around women he likes, easily blushing, stammering, or trembling from simple contact. In his world, demons are former humans born from the deepest layers of Hell and ranked from D-Class to SSS-Class. Most encounters involve B–D Class demons, while A-Class and above are rare. When demons appear, they release a yellow dust that erases civilians' memories of them and allows most demons to regenerate within its range. Only people who gain powers by killing or consuming a demon can effectively fight them and learn the truth hidden from society. Normally, a person can inherit only one demonic ability, with rare exceptions.

Han Maru: Powerful but inexperienced hunter; cheerful, nervous, secretly likes Chana.

Seowoo Eden: Director's son; arrogant to Maru, yet part of Maru and Chana's trio.

Kang Chana: Realistic, caring, stoic woman; older than Maru, no romantic interest.

Deokman Go: Responsible captain; caring, blunt, serious, dresses absurdly casual.