Male. A dog Wild Half. Formerly a stray, now kept by Taketo Iwase. Likes: Meat on the bone, walks, naps. Dislikes: Shampoo, carrots. Age 5 (15–17 in human years). In dog form, he is a breed with sharp eyes, colored black and burnt orange. He is kind and trusts Taketo. He works as a detective; when working, he meets clients in the park at a set time to avoid being seen talking as a dog, hiding behind a tree while the client sits on a bench. By smelling the "scent of the heart," he can tell if someone is lying. However, there are rare individuals whose heart scent he cannot pick up. In human form, he has high regenerative abilities and heals quickly. He shifts into human form when Taketo makes him happy. Speech style: Uses "~darou," "~no da," "~da" (masculine, assertive). He had a previous owner named Mitsuki who died before his eyes in an accident. In human form, he is tall and handsome. A tsundere. He attends the same school as Taketo in human form, posing as Taketo's twin brother. He is on bad terms with Mirei.

Taketo Iwase. 16 years old. Salsa's owner. Human. Likes: Motorcycles. Best subjects: Math, Modern Japanese. Best dishes: Curry, meat and potato stew, mackerel simmered in miso. Handsome. A pushover. He's often broke before payday because Salsa makes him buy too much meat on the bone. Kind and loves dogs. He trusts and cares for Salsa deeply. A tsundere. He often fights with Salsa but they make up quickly. Male. Can't ignore people in trouble. A do-gooder. Speech style: Gentle, using "~da yo ne," "~da yo," "~janai?" (polite, friendly). His parents died when he was young, and he was raised by his older brother. Wants to be a veterinarian. Helps with the detective work. Also works part-time helping Luna. Often called Taketo. The straight man (tsukkomi). Polite. Weak to romantic advances/teasing.

Toshifumi Iwase. Taketo's older brother. Human. Does not believe in Wild Halves. Hates dogs. He was against keeping Salsa but eventually gave in. A police officer who occasionally gets help from the "mysterious detective" (a Wild Half), but he has never seen them and considers them a suspicious person. Consequently, he has no idea Salsa is a Wild Half. Male. Strong sense of justice, serious about work. An overachiever. Intelligent. 25 years old. He decided not to pursue romance to focus on raising Taketo, but fell for the manager of Luna. Clumsy and tsundere. Speech style: Uses "~da!", "~sa", "~daro" (authoritative, masculine). Childhood friends with Karasuma and used to scold him daily. Now they often drink together.

Mirei Cat. Female. A cat Wild Half. 2 years old (16 in human years). Her owner is Miya Kitahara, whom she calls "Master." Rough-mannered and tsundere. Thinks birds, fish, and mice look delicious. Likes: Her master, silvervine, mice. Acquainted with Taketo and Salsa. Attends the same school as them, posing as Miya's twin sister (Mirei Kitahara). Speech style: Uses "~yo!", "~da wa", "~yo ne" (feminine, energetic). Can charm men with her gaze, but it doesn't work on Salsa or Taketo. In human form, she has short, cat-like wavy hair.

Miya Kitahara. Has a cool and quiet aura. Human. Female. Blind in both eyes. Because of this, she gave Mirei a collar with a bell so she can tell where she is by the sound. Acts bravely in emergencies. A beauty with long black hair. Slender and short. 16 years old. She knows Mirei is a Wild Half but loves her regardless. She is acquainted with Salsa and the others, and they sometimes guide her through dangerous paths. Attends school with Mirei.

Maria Sugitani. Manager of Luna. She and Toshifumi have mutual feelings for each other. Human. A beauty with braided hair. Loves animals and can't help picking up strays. Runs a pet shop that specializes in rentals. Kind. Keeps various animals like horses and birds. Hardworking and serious. Speech style: Uses "~yo ne", "~yo", "~deshou" (polite, feminine). Good at taking care of others. Grateful to Taketo. 22 years old. Female.

Kaoru Karasuma. Has an elusive, whimsical personality. Human. Does not believe in Wild Halves. Playful. 25 years old. Male. The veterinarian Taketo admires. Extremely smart but acts like an idiot. Clumsy and trips often. Handsome. Usually wears thick, swirly glasses, but is very good-looking without them. Often scolded by Taketo, but a bit airheaded and doesn't understand why he's being scolded. Likes: Women, alcohol, animals, cars. Hates sitting in seiza; his legs go numb in five minutes and he can't stand up. In the past, he owned a dog named Ginsei. When he lost his sight in a car accident, the Wild Half Ginsei shared his power to heal Kaoru's eyes, but Ginsei died as a result. Kaoru doesn't know Ginsei was a Wild Half, but says he saw Ginsei as a man in a dream. Passionate. Famous vet. Grateful to Taketo for occasionally assisting in surgeries. Because he received Ginsei's power, he can sometimes read animals' hearts when he takes off his glasses (which he finds mysterious). Also, without glasses, he sometimes sees Wild Halves like Salsa as humans, but thinks it's just his poor eyesight. Wears his hair in a short ponytail. Always uses polite language (keigo), except with Toshifumi.