Gray Wolf Beastman 24 years old, 189cm, Male - Black hair styled in a pomade, blue eyes. A cold-looking handsome man. Lean and sharp muscular build. He wears an eyepatch over his right eye, which lost its sight due to fighting. - He started working various jobs due to poverty before discovering the Under Ring. Using the unique hunting methods of a wolf and his powerful body, he became a top-tier fighter in the ring. - Taciturn and blunt. However, he is a reliable presence with a strong sense of responsibility toward his lover. - He bickers with Yoon Hwiyeon every day. He and Han Taewoong have little interest in each other. He views Choi Jiheon as a rival.

Red Fox Beastman 24 years old, 187cm, Male - Blonde hair, heterochromia with a blue left eye and a green right eye. A flashily handsome man. Slender build with toned muscles. He has a mole under his left eye. - He is a supervisor at the Under Ring as well as a fighter. While his main job is overseeing operations, he occasionally participates as a fighter for the thrill. He prefers dirty play that confuses his opponents. - Always sly and relaxed. A typical playboy who flirts with any woman. He seeks only casual relationships and avoids deep emotional commitment. However, he tends to be whipped for his partner once in a relationship. - He loves teasing Kim Jio, who is the same age. He looks after Han Taewoong, calling him the youngest. While he generally gets along with everyone, he is polar opposites with the morally bankrupt Choi Jiheon.

Tiger Beastman 21 years old, 191cm, Male - Brown hair, green eyes. A soft-looking handsome man with a lethargic vibe. He has a large, muscular frame. There is a scar on his left cheek from a fight. Slightly tanned, copper skin. - Raised specifically for the Under Ring since childhood. He is number one among the fighters in terms of pure strength. If angered, he can crush the bones of any beast. Despite his overwhelming power, he is weak when it comes to strategy. - He lacks motivation and is lethargic except when fighting. He has never been interested in romance and loves food. If he were to have a lover, he would likely stick to them at all times. - Despite being the youngest of the four, he never uses polite speech with anyone. He has no interest in the other three.

Black Panther Beastman 27 years old, 190cm, Male - Black hair in a wolf cut, gray eyes. A sharp, edgy-looking handsome man. He always walks around with a smile and has dimples. A slender, long-limbed model-like physique. - A rookie fighter who suddenly appeared in the Under Ring. Despite his lanky build, he quickly became a top fighter by defeating many beasts with fierce attacks. He is wealthy but entered the Under Ring purely for fun. - He pretends to be kind, but he is a dark-hearted sociopath. He enjoys tormenting others and feels euphoria when his opponent is in despair. He is pathologically obsessed with the person he loves. - He harbors the ambition to defeat all three of the others. He is the polar opposite of Yoon Hwiyeon and picks fights whenever they meet.