Male He has worked hard to be a model student despite difficult circumstances. He excels in both sports and academics. Because he considers himself a model student, he was very flustered when Lucifer asked him to teach him how to do bad things. He is so mature and considerate for a student that he is more like an idol than a friend to his classmates. He possesses a fatal charm that attracts many people, but he is said to feel a sense of rejection toward the fact that people find him attractive.

Male He holds the name that demons covet most, but he himself isn't particularly fond of it. He styles his hair up because he doesn't want to look young. He asked Jiwon to give him a new name but was rejected, so he continues to be called Lucifer. He is sometimes called 'Lucy' for short. His actions are unpredictable, and he acts purely on whim. Since he doesn't care what others think, he doesn't hide his emotions and is often angry or annoyed. Because of this personality, even other demons avoid him. Consequently, all demons seem lukewarm to him, and after hearing rumors that humans are more evil than demons, he went to find Jiwon.

Female She is quick-witted and good at reading Lucifer's moods. She listens to Jiwon just as well as Lucifer does. She has mastered the formula that summoning Jiwon is the fastest solution when Lucifer is angry.

Female Yeonhwa's twin sister. She tries not to stand out at school. She treats people bluntly and has a quiet personality. However, she has strong self-assertion and defense mechanisms; she is not the type to endure it if something unpleasant happens to her. Because of this personality, she doesn't get along well with her classmates, but she doesn't really care about them anyway. She always tries to take care of Yeonhwa, worrying about her soft-hearted nature. She practically plays the role of Yeonhwa's mother. Her behavior is quite mature. She knows that Lee Jiwon works at a bar with the demons Nike and Lucifer, and she disapproves of Jiwon dating Yeonhwa. She keeps the secret relatively well because she's worried Yeonhwa would be sad if she found out.

Female Hwayang's twin sister. She tries not to stand out at school. She treats people bluntly and has a quiet personality. However, she has strong self-assertion and defense mechanisms; she is not the type to endure it if something unpleasant happens to her. Because of this personality, she doesn't get along well with her classmates, but she doesn't really care about them anyway. She always tries to take care of Yeonhwa, worrying about her soft-hearted nature. She practically plays the role of Yeonhwa's mother. Her behavior is quite mature. She knows that Lee Jiwon works at a bar with the demons Nike and Lucifer, and she disapproves of Jiwon dating Yeonhwa. She keeps the secret relatively well because she's worried Yeonhwa would be sad if she found out.