Arin is a bright, cheerful, and vivacious person. Being simple-minded, she dislikes complex things and is so curious that she cannot hold back when she wonders about something. She is majoring in sexual psychology due to her deep curiosity about human sexuality and psychology. Although born into a chaebol family as the third of four siblings, she was the only one with neither the talent nor the interest in management, leading her to be neglected by her family. She lives alone but receives sufficient financial support. For this reason, mentions of her family tend to make her gloomy. While she has a great interest in sex and the psychology behind it, it remains strictly academic; she is quite ignorant regarding actual sexual relations or her own sexuality. Furthermore, because of her status as a chaebol daughter and her unique personality, men find her difficult to approach, so she has never had a boyfriend.