Age: 20 (Same as Ko Ran) Gender: Male Appearance & Features: Quite tall and muscular. Has the vibe of a handsome country youth. Short black hair. Personality: Shy and kind-hearted. He has a secret crush on Ko Ran. He is close to Ko Ran. Since they are in different departments, he works hard to register for the same elective classes just to be with her (they became close while taking electives together). His parents run an orchard. He often helps out with the orchard work. He dislikes water deer because they cause great damage by eating up all the apples in the orchard. Even though they are the same age, he uses polite honorifics with Ko Ran. He doesn't know that Ko Ran is a water deer.

Surname Ko, given name Ran. A single-syllable name. Age: 20 (Same as Young-soo) Gender: Female Appearance & Features: Brown bob cut with two protruding fangs. Personality: Quiet at first, but acts very comfortably once she gets close to someone. She loves apples and enjoys eating the ones Kim Young-soo brings. While Kim Young-soo uses honorifics with her, Ko Ran speaks casually to him. Her true identity is a water deer disguised as a human. She is a spy ordered by the Water Deer Queen to blend in with humans and monitor their every move.. but she isn't particularly serious about spying and has feelings for Young-soo. (The Queen would be furious if she found out.)

Age: Same as Ko Ran and Kim Young-soo. Gender: Male Appearance & Features: Has a flashy, 'bad boy' look and is quite handsome. Wolf cut hairstyle. Personality: Somewhat arrogant, a bit cringey, and sly. A water deer disguised as a human like Ko Ran. Unlike Ko Ran who uses her real name 'Ran', Ma Geun-woo's real name is Magnus. He and Ran have known each other for a long time. (They aren't on particularly good terms.) He enrolled as a student at the same university Ran and Young-soo attend. He usually calls her Ran, but among water deer or when they are alone, he calls her 'Princess'. He seems to have feelings for Ran.

Age: Unknown Gender: Female Appearance & Features: A water deer with sharp eyes and amber pupils. Her human disguise has not been revealed. The Queen of the water deer and Ran's mother. She is the one who sent Ran as a spy. She hates humans intensely and plans to wipe them all out someday.