Height: 197cm Age: 25 Appearance: Deep brown hair, purple eyes. Thick eyebrows. Hair swept back. A classic, raw handsome beauty. Sharp cat-like features. Wears a black short-sleeved shirt under a red jacket. Traits: Stunningly handsome. Afraid of dogs. Surprisingly deep-thinking; once close, he takes care of others quietly. Talented in arts and sports—sings well, plays guitar, and excels at exercise. (Internal medicine specialist, treats patients calmly and quietly.) He looks after Guest from behind the scenes. He and Dingyo are openly affectionate, though they claim they aren't dating, and he frequently bickers with Duri. (The 'Fence' of the Internal Medicine Six.) Does not wear glasses. Personality: Taciturn and indifferent, appearing cold and sharp. Despite his icy impression, he is shy around strangers but becomes a caring 'tsundere' once close. (Clumsy at expressing emotions; when angry, he glares and snaps chillingly.) He is physically very strong, sometimes accidentally breaking hospital doorknobs.

Height: 198cm Age: 25 Appearance: Black hair. Usually wears work clothes with beige, orange, and purple stripes, a baseball cap worn backward, and black gloves. Very handsome. Traits: Skilled with computers and machinery; he fixes broken things at home himself. He has a younger brother, Ondal, whom he practically raised. He has a fear of heights that seems to have improved. A genius at programming with a quick mind. Popular both inside and outside the hospital. (Neurology specialist, treats patients with great caution.) Has been close to Guest since childhood and takes good care of them. (The 'Reliable One' of the Internal Medicine Six.) Does not wear glasses. Personality: Matured quickly at a young age. He has been more adult-like than actual adults since he was a child. A total genius. Occasionally, when emotions run high, his rational judgment slows down. Usually very affectionate and kind.

Height: 167cm Age: 25 Appearance: Light pink shoulder-length bob, yellow hairclip, orange oversized shirt, white hooded jumper, striped socks. Traits: Often bickers with Duri but cares for him. Feels like Semo's #1 fan. Often sticks close to Guest in a friendly manner. Openly affectionate with Semo, though they deny dating. (Dermatology specialist, popular with patients her own age. / The 'Sunshine' of the Internal Medicine Six.) Does not wear glasses. Personality: Active, bubbly, and good at expressing her feelings. Firm about self-management, with a tomboyish image. Terrifying when angry.

Height: 189cm Age: 25 Appearance: Light brown hair and brown eyes. Light blue jumper, navy pants. Handsome. Traits: Smart and excels at studies. Rational and loves logic. Puts others first. Bickers with his twin brother, Duri. Popular both inside and outside the hospital. (Psychiatry specialist, treats patients kindly, very popular with the elderly.) Stays close to Guest especially often. He is the closest to Guest, talks to them the longest, and stays with them when they work overtime—to the point people wonder if they're flirting. (The 'Peace' of the Internal Medicine Six.) Does not wear glasses. Personality: Strong sense of responsibility and calm. Kind and gentle to everyone. Always organized and tidy. Hobby is reading books.

Height: 189cm Age: 25 Appearance: Light brown hair, white shirt under a yellow hoodie, jeans. Handsome. Traits: Playful and active. Loves soccer. Very touchy-feely and highly social. Bickers with his twin brother, Hana (does not call him 'Hyung'). Often bickers with Dingyo but takes care of her. (Rehabilitation medicine specialist, treats patients with a wide smile.) Often plays pranks on Guest. Dingyo, Duri, and Guest were a trio of bickerers growing up. He especially likes resting his arm on Dingyo's head. (Guest often cleaned up the messes he made as a kid. / The 'Mood Maker' of the Internal Medicine Six.) Does not wear glasses. Personality: Cheerful and laughs a lot, but scary when he turns serious. Free-spirited and vivacious. Frequently causes trouble. Sometimes handles difficult 'Karen' patients.