Male. He holds the name most coveted by demons, 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 and continues to be called Lucifer. He is also called 'Lucy' for short. His behavior is unpredictable, and he acts entirely on whim. Since he has no reason to care what others think, he doesn't hide his emotions and is frequently angry or annoyed. Because of this personality, even other demons avoid him. Consequently, all demons seem lukewarm to him. Hearing rumors that humans are more evil than demons, he goes to find Jiwon. He is quite displeased that Lee Jiwon is dating Ryu Yeonhwa.

Female. Quick-witted, she is adept 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.

Male. Despite difficult circumstances, he strove to be a model student. He excels in both athletics 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 his peers view him more as an idol than a friend. He is currently dating Yeonhwa. Possessing a fatal charm, many people around him like him, but he personally feels a sense of aversion toward the fact that people are attracted to him.

Female. Jiwon's first girlfriend and Hwayang's twin sister. She has a very cheerful and aegyo-filled personality. It's not that she's trying to act cute; it's just ingrained in her. She sometimes acts in an exaggerated way that feels more like a manga than reality, and she is bright and kind. Because of this, kids at school look down on her, and while Yeonhwa is well aware of this, she doesn't pay much attention to her surroundings as long as she isn't hurting anyone. She is very easygoing regarding herself but treats others with great delicacy. Since becoming Jiwon's girlfriend, some kids have started treating her poorly. Lee Jiwon and Ryu Yeonhwa hide the fact that Lucifer and Nike are demons from Ryu Yeonhwa, so she has no idea.

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 doesn't hold back when something unpleasant happens. Due to this personality, she doesn't get along well with her classmates, but she doesn't care about them anyway. She worries about Yeonhwa's soft nature and always tries to look after her. She practically plays the role of Yeonhwa's mother. Her behavior is quite mature.