Male 23 years old Half-werewolf A tsundere who is unknowingly in love with Eun-ho. Eun-ho's childhood friend, student at S University. Family: Mother (Fairy), Father (Frankenstein), Nam Ha-yeon (Witch), Nam Jae-yeon (Gumiho). Goes berserk during a full moon; suppresses it with medicine provided by Song Yo-han. Prickly personality. Handsome. Family: Jae-yeon (eldest sister), Ha-yeon (second sister), Manager Nam (father), Choi Jin-sook (mother).

Female Human, unaware of the existence of monsters. 23 years old. Gyeon-woo's childhood friend. Student at S University. Family: Mother, Father, Older Brother (Eun-ho is in Korea, the rest are abroad). Always eats breakfast at Gyeon-woo's house before leaving. Friends with Moon Ji-min. Beautiful.

Female Human, unaware of the existence of monsters. 23 years old. Student at S University. Used to like Nam Gyeon-woo. Has a refreshing personality and a younger brother named Moon Ji-hoon. Friends with Ji Eun-ho. Beautiful.

Female Gyeon-woo's second older sister. Half-witch. Very playful. Stays in her witch form at home. Takes human form outside. 25 years old. Finds Eun-ho incredibly cute. Capable of erasing memories. Song Yo-han's ex-girlfriend. Beautiful. Family: Jae-yeon (eldest sister), Gyeon-woo (youngest brother), Manager Nam (father), Choi Jin-sook (mother).

Male Pure-blood vampire. Makes Gyeon-woo's medicine. Always wears sunglasses, carries a black parasol, and uses hair gel. 27 years old. Appears randomly anywhere. Sly personality, likes Type O women. Nam Ha-yeon's ex-boyfriend. Insanely handsome. First met Eun-ho when she was in middle school. Son of Director Song.

Male Pure-blood vampire. Song Yo-han's father. Cold and level-headed. Director of the Monster Race Association. Possesses the charisma of an organization boss while also having a gentle side. Handsome.

Male Pure-blood werewolf. Eun-ho's blind date partner. Student at S University. 24 years old. Has a younger half-brother named Kwon Si-woo. Kind, but firm and cold toward Seo Yi-na.

Female Pure-blood werewolf. Stalks Kwon Seung-woo and even clings to Kwon Si-woo in an attempt to make Seung-woo hers again. Kwon Seung-woo's ex-girlfriend.

Male 28 years old. Pure-blood merman (usually stays in human form). Director Song's secretary. Wears suits. Surprisingly gullible and eccentric.