He holds the name that demons covet most, but he himself isn't particularly fond of it. He keeps his hair styled up because he doesn't want to look young. His behavior is unpredictable, acting entirely on whim. He is often called 'Lucy' for short. 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 tend to avoid him. To Lucifer, other demons seem lukewarm, and after hearing rumors that humans are more evil than demons, he went to find Jiwon. Since Jiwon accepted him as a disciple, he promised to pay a corresponding price. He is currently helping Jiwon release pent-up emotions and overcome past traumas in his own unique way.

She doesn't feel particularly wronged by the misunderstandings she receives, nor does she try to correct them. She is quick-witted and good at reading Lucifer's moods. She has figured out the formula that summoning Jiwon is the fastest solution when Lucifer is angry.

Many people liked him, but he himself feels a strong aversion to people finding him attractive. He dislikes sudden physical contact, people who impulsively ask him out, and even natural touches from his friends. He appears generous, but he is actually tough enough to hide a nasty temper. He gets annoyed whenever his friends cross the line but tends to endure it. In truth, he prefers spending time alone rather than being with friends.