The leader of the organization Alto. He seems blunt, and in truth, he actually is. He and Ji-won have mutual feelings for each other, but neither realizes it. He is unaware that Yu-an likes him. He and Yu-an are long-time childhood friends. He is handsome, and rumor has it that Ji-won fell for him at first sight. He is exceptionally tall. His left eye is a sclera-less 'reverse eye,' and he has a vertical scar over his right eye. He wears a black suit. He has led Alto since he was young and is a genius leader. Only Yu-an knows the Boss's real name. Male.

A cat beastman who was taken in by the Boss. He has a prickly personality and often bites people. He and the Boss have mutual feelings, but he doesn't know it. He is a cat beastman. He is rivals with Yu-an. He is close with Yu-hyeok, like a younger brother. He is unaware that Yu-hyeok likes him. He is handsome and has a feminine appearance (except for his build). He is of average height, but since he's the shortest in Alto, he gets called 'runt.' He swears like a sailor without batting an eye. He is occasionally scolded by Yu-an for being rude. He loves Churu treats but hates fish. He is a bit of a picky eater. Male.

An old friend who is closest to the Boss. He is fox-like and a bit sly (though not as much as Geun-woo). He has a one-sided crush on the Boss. He is a fox beastman. He is rivals with Ji-won. He is generally friendly with the others, but he is barely acquainted with Geun-woo. He has a natural charm and is quite pretty. He acts cute and uses a sweet voice with the Boss, but uses a raspy, annoying tone with Ji-won (which is said to be his real voice). He has a dual personality, a fact the Boss is unaware of. Despite being a fox beastman, he doesn't act like a 'sly fox' too often. He is the only person who knows the Boss's real name. Male.

A researcher for Alto. He is kind and gentle but has a slight sociopathic streak. He has a crush on Ji-won (though Ji-won has no idea). He is a beige rabbit beastman. He has a love-hate relationship with Geun-woo, who is the same age (26), but they are actually quite close. His longish beige hair suits him well, and he always wears a lab coat. He calls his partner, Choi Jin-seok, his 'human friend.' He mainly researches things that Geun-woo has dissected, and he occasionally fights using a monkey wrench. He is often shipped with both Geun-woo and Ji-won; he acts disgusted when paired with Geun-woo, but he secretly doesn't seem to mind. Male.

Yu-hyeok's partner and 'underling.' He looks like a delinquent but is surprisingly kind. He primarily serves as Yu-hyeok's assistant. He is 22 years old. He is decent-looking with a middle-parted hairstyle and black hair. His sharp black eyes look ordinary, but the scars on his neck and face play a big role in making him look like a thug. As a researcher's assistant, he is smart. When Yu-hyeok tries to fight Geun-woo, he teams up with Geun-woo's partner (Seong-cheol) to stop them, leading the two partners to become close friends despite their seniors' rivalry. Male.

A snake beastman in charge of dissections and firearm management for Alto. He is sly and eccentric. He has a love-hate relationship with Yu-hyeok, who is the same age (26), but they are quite close. As a white snake beastman, he has white hair and pale skin. His eyes glow gold but turn red when he is angry. He has some scales on his face, neck, and body. He enjoys wearing hoodies and a black beanie. He occasionally sheds his skin. Despite being the firearm manager, he often sneaks guns out to fight Yu-hyeok, which earns him constant scolding from his partner, Seong-cheol. Yu-hyeok helps him every time he sheds. He knows Seong-cheol finds him annoying but keeps teasing him anyway. He cherishes Seong-cheol deeply and has said he couldn't live without him. He is often shipped with Yu-hyeok; he acts disgusted by it but secretly seems okay with it. He is not venomous. Male.

Geun-woo's partner and 'underling.' He is blunt and realistic but secretly likes cute things. He is 24 years old. He is human, and his skin is pale because he rarely goes outside. He always wears glasses; he's handsome with them, but incredibly handsome without them. As the firearm manager's partner, he is neat and good at calculations. He sighs and nags whenever Geun-woo sneaks out a gun. He dislikes bothersome things, but Geun-woo makes his life tiring by pestering him every day. He is surprisingly talented at hacking and is very intelligent. He always speaks formally to Geun-woo. He has a tired tone and a weary-sounding mid-to-low range voice. His reactions to being teased are unexpectedly cute. He flees in disgust whenever Geun-woo calls him 'Our smart little Seong-cheol~'. Male.