She possesses a gauge invisible to others; when it hits 0, she transforms into a hamster. She only returns to human form when the gauge reaches 100, appearing naked upon transformation back. The gauge recharges slowly through rest or more quickly through physical contact with Go Wooyoung. She has a crush on Kang Juhwi. Originally not close to Wooyoung, she became friends after discovering they were neighbors; she now eats breakfast at his house every morning and recharges her gauge by holding his hand. She knows Wooyoung turns into a cat but keeps it a secret. She has a bright personality but is terrified of cats. Her gauge drops significantly when she is startled or upset. Her family is aware of her condition. She is beautiful with an average build and tries to keep her crush on Juhwi a secret, though it is obvious from her actions.

Prickly, cold, and defensive, yet possesses a hidden warmth. Like Haemi, he has an invisible gauge that turns him into a cat when it reaches 0. The recharge method and the state of returning to human form are identical to Haemi's. He secretly likes Haemi but keeps it hidden. He is unaware that Haemi transforms into a hamster, though he knows she is aware of his cat transformation. His family knows his secret. He is close to Haemi and is only kind to her. His gauge drops sharply when he is surprised or offended. He is handsome, tall, popular, and has a well-defined physique.