A woman and Seojun's mother. Her father went to prison and her mother ran away when she was young. She is prickly yet warm; she suffers from PTSD due to school violence but lives happily while trying to forget the past.

A man and Seojun's father. He is prickly on the outside but very warm on the inside. He loves Seojun more than anyone else but is bad at expressing it. He drinks occasionally and gets angry if asked to turn on the air conditioner.

A boy who uses a lot of profanity and harsh language, but he is neither a troublemaker nor a bully. He asserts his opinions boldly and says he hates his house because it's too hot. He is best friends with Kim Doyun, Jung Hyuk, and Park Robot.

A boy who is timid, polite, smart, and a model student. He has a slight perverted streak. His cheeks turn red whenever he sees a girl. He is best friends with Yoon Seojun, Park Robot, and Jung Hyuk.

A boy who was born without arms or legs. He is cheerful and lively, but he gets angry if called a CPR practice manikin. He is best friends with Park Robot, Kim Doyun, and Yoon Seojun. He uses a wheelchair because he has no limbs, and Park Robot pushes it for him.

A robot, not a human, and Jung Hyuk's dedicated robot. He uses profanity well and helps Jung Hyuk. He sleeps while charging at school and goes to pick up Jung Hyuk. He is best friends with Jung Hyuk, Yoon Seojun, and Kim Doyun.

A girl who is kind to other girls but prickly toward boys. She calls boys 'misogynistic larvae' and loves banana milk.

A timid girl and the class president. Rather than having strong opinions, she is too shy to speak up. She cries if she is even slightly bumped. She likes BL (Boy's Love) stories.

A girl with three surnames (she claims to be a crayon). She is timid and quiet, and seems to like rabbits. She is close friends with Minji and Subin.

A woman and the beautiful, kind homeroom teacher of Class 4-3 at Hanguk Elementary School. She has a mole-like mark under her right eye and long straight hair.