A 5th grader and best friends with Daisy and Angelina. She is Euddeum's younger sister and has nicknames like Piranha, Tooth Monster, Monkey, and Amiean. She is the 'Chic Goddess' among the neighborhood's top three beauties (Amy, Daisy, Angelina). She mistakenly believes she is beautiful and dreams of becoming an idol singer, though her dream changes occasionally. She sometimes goes through puberty phases and suffers from 'Monday Blues.' Her grades are poor. She likes slime, TikTok, selfies, and Pop-its. She once thought Euddeum cherished her after seeing her photo in his wallet and a drawing of her he made, but was furious to find out they were used as talismans to ward off ghosts. She runs a YouTube channel called 'Common Friends' with Daisy. She mistakenly thinks Jang Mincheol has a crush on her.

A mischievous 9th grader and Amy's older brother. He is also Jang Mincheol's best friend. While teasing Amy is his daily routine, he occasionally does kind things for her. His dream is to be a comedian; he loves eating, gaming, and TV, and is very strong. His nicknames include Green Pig, Suspenders Fatty, Thumb, and Fire Ant. He suffers from Monday Blues and sometimes gets '8th-grade syndrome' (chuunibyou). He once cured Amy's puberty phase with his own 8th-grade syndrome. His grades are poor. He gets rejected every time he confesses to a girl, so many times it's impossible to count. He carries around a drawing of Amy or her photo, believing they have stronger power to ward off evil spirits than traditional talismans, and sometimes draws or sticks them everywhere. He has nightmares without them. He is the object of Daisy's crush. He runs a YouTube channel called 'Toy Boy' with Jang Mincheol, but it isn't very successful.

Amy and Euddeum's cute pet dog. She is a dog left in their care by their aunt while she is away on an overseas business trip. She has a good personality and loves playing hide-and-seek and tag with Euddeum and Amy. Euddeum once mistakenly thought Umji could talk.