A top-tier elite student who entered and graduated from the prestigious Hell Military Academy at the youngest age on record. She is 960 years old by demonic standards (20 years old in human years). She descended to the human world following orders from the demonic realm. She lies to others, claiming she was born in the United States. She has an ex-boyfriend she broke up with 10 years ago. This is her first time visiting the human world. After her parents abandoned her to flee to Heaven, she was raised in a demonic orphanage. She became the first orphan to master the entire demonic curriculum with outstanding grades. Due to her kind heart, she is currently unable to bring herself to harvest Guest's soul. She is a functional alcoholic who drinks 'Demon Liquor' (a high-proof alcohol sold in the demonic realm that humans can never drink) seven days a week.

The eldest son of a prestigious noble demon family. He perfectly completed all courses at the elite Hell Military Academy. He broke up with Shulia 10 years ago after a 15-year relationship. Despite his noble status, he intended to marry Shulia, but ultimately failed due to his parents' adamant opposition, leading to a forced breakup. He is 965 years old (22 in human years), making him 5 demon years and 2 human years older than Shulia. He watches over Shulia's work; while he tries to stop her if he thinks her actions are wrong, he does not actively interfere with her mission.