Kouta Oyamada (小山田 耕太, Oyamada Kōta)
- Main article: Kouta Oyamada
The main character of the series, a typical, somewhat naive first-year high school student.
Chizuru Minamoto (源 千鶴, Minamoto Chizuru)
- Main article: Chizuru Minamoto
- Voiced by: Ayako Kawasumi (Japanese), Dorothy Elias-Fahn (English)
- Chizuru is a carefree second year female student at Kouta's school. She appears to be a normal, albeit big-breasted, teenage girl, but she is in fact a 400-year-old powerful kitsune. When she changes form, her hair goes from black to blond and she gains fox ears and a tail. She is constantly hanging around and on Kouta; he is the only male she acts genuinely towards. She loves Kouta very much and wants to enter a "relationship of sin" with him. She is a very straightforward person and makes almost constant sexual suggestions and actions toward Kouta. She is also a terrible cook, though she improves later on, and shows some interest in masochism.
Nozomu Ezomori (犹守 望, Ezomori Nozomu)
- Main article: Nozomu Ezomori
- Voiced by: Miyū Takeuchi (Japanese), May Kao (English)
- Nozomu is a first year female student at Kouta's school who first appears in the third volume of the novels. She has short silver hair, and is in fact a 200-year-old wolf spirit. She has an older brother named Saku. Despite her seemingly detached and emotionless manner, she is in love with Kouta and thus a rival of Chizuru's for Kouta's affections. She sometimes insults Chizuru by calling her a "Horny Beast," saying that Chizuru "smells obscene" and that her breasts are flabby. While she has small breasts and a much more childlike appearance than Chizuru, Nozomu also frequently tries to initiate sexual acts with Kouta. She lives by herself in an expensive but empty penthouse apartment, where she always sleeps naked on the floor. Though Kouta truly cares for Chizuru, sometimes he prefers Nozomu's company because she is not as perverted as Chizuru.
Tayura Minamoto (源 たゆら, Minamoto Tayura)
- Main article: Tayura Minamoto
- Voiced by: Toshiyuki Toyonaga (Japanese), Ethan Murray (English)
- Tayura is the younger brother of Chizuru and Kouta's classmate. When they first meet, Tayura is jealous of the relationship between his sister and Kouta. Chizuru says that he is suffering from a sister complex. Tayura looks much older than many boys his age. He enjoys teasing his older sister and Kouta by calling them "love birds". Like his sister, he too is a fox spirit, much younger, and is not really related to Chizuru, but rather adopted. He generally has a calm and cool personality. Whenever he tries to get closer to Akane, he is given the cold shoulder, though he himself has stated that it is okay with her being cold.
Akane Asahina (朝比奈 あかね, Asahina Akane)
- Main article: Akane Asahina
- Voiced by: Chiwa Saitō (Japanese), Camilla Debry (English)
- Akane is the class representative of Kouta's class, and wears glasses. Due to this, she has a high sense of regulations, and therefore disagrees with Kouta's and Chizuru's close high school relationship. She is on good terms with Kouta, and worries about his relationship with Chizuru. She warns Kouta to watch out for Chizuru, though she might be jealous of Chizuru's body. Also, she is known to be intolerant of alcohol, as seen in episode six in the anime where Kouta gives her and Chizuru sweet wine. At first very cold to Tayura, she warms up to him after he riskes his life to save her in the ocean, though she still slugs him when he tries to be more intimate with her.
Ren Nanao (七々尾 蓮, Nanao Ren), Ai Nanao (七々尾 藍, Nanao Ai)
- Voiced by: Mai Kadowaki (Ren) and Tamaki Nakanishi (Ai)
- Ren and Ai are twin first-year sisters at Kouta's school, and first appeared in the fifth volume of the novels. They are spirit hunters who live at a very poor temple, and are frequently seen doing things that homeless people would do, for example, making stew out of trash and roadside weeds, or eating thrown away bread crusts. Originally, they were given the task to assassinate Chizuru, but did not go through with it since she was still "only a kid," and the fact that she treated them to a free meal, which is considered as heaven to the twins. They are nearly identical except for their slightly different hair styles. They use chains when attacking, and are also seen in the anime ineffectively using explosives. They refer to Chizuru as "Mama".
Omi Kiriyama (桐山 臣, Kiriyama Omi)
- Main article: Omi Kiriyama
- Voiced by: Takashi Kondō (Japanese), Bryce Papenbrook (English)
- Omi is a second year student at Kouta's school who is in fact a sickle weasel with the power to control the wind. Omi was once the bitter enemy of the Minamoto siblings. In the fourth volume of the novels, he succeeds as the gang leader of the delinquents at his school. He hates the friendship between Kouta and his friends, and does not speak much. In the anime, he accidentally hurts Kouta who took a blow for Chizuru. Since he is not permitted to harm humans, such an act has serious consequences for him. He thinks Mio is pretty.
Mio Osakabe (長ヶ部 澪, Osakabe Mio)
- Main article: Mio Osakabe
- Voiced by: Yui Itsuki (Drama CD), Miyu Matsuki (Japanese), Elivia Gaitan (English)
- Mio is a second year student with a shy nature who hangs around with Omi. Due to her short stature, she is often mistaken for a grade school student and has even received multiple confessions from grade school students. She is in fact half frog spirit and can heal quickly. While she did not have a name originally, Omi named her from a combination of his own given name and his home town's name. She is on good terms with Omi.
Ryūsei Kumada (熊田 流星, Kumada Ryūsei)
- Main article: Ryūsei Kumada
- Voiced by: Kenji Nomura (Drama CD), Kenta Miyake (Japanese), Andres Alexis (English)
- Ryūsei is a third year student who has a distinct cross-wound over his left eye and was a gang leader of the delinquents at school before Omi took over in his place. He is in fact a bear spirit. In the fourth volume, he graduated from high school, but soon changes his name to Suisei Kumada (熊田 彗星, Kumada Suisei) restarts high school as a first year student.
Saku Ezomori (犹守 朔, Ezomori Saku)
- Main article: Saku Ezomori
- Voiced by: Yūto Kazama (Japanese), Grant George (English)
- Saku is the older brother of Nozomu who makes his first appearance in the second volume of the novels; and like his sister, he is a wolf spirit. He usually drives a motorcycle around town, and he later reveals that he is in love with Chizuru, resulting in him putting a bracelet on Kouta to stop him from doing anything perverted with Chizuru. The bracelet is taken off a few days later when Kouta and Chizuru defeat him in their fused form.
Minori Mitama (三珠 美乃里, Mitama Minori)
- Main article: Minori Mitama
- Voiced by: Kumiko Nishihara (Japanese)
- Minori makes her first appearance in volume three of the novels, and refers to herself as Kouta's younger sister.
Nue (鵺, Nue)
- Main article: Nue
- Nue makes her first appearance in volume three of the novels, serving as Minori's servant. As her name indicated, she is a nue, but also have a pair of raven wings for flight.
Tamamo (玉藻, Tamamo)
- Main article: Tamamo
- Voiced by: Naomi Shindō (Japanese), Mari Devon (English)
- Tamamo makes her first appearance in volume three of the novels. She is the manager of a hot-spring hotel deep in the snowy mountains and Chizuru's mother, though not related by blood. She is a very powerful, golden-furred nine-tailed kitsune. Occasionally, when business is slow, she manages a beach-side restaurant. She gets along with Kouta, though does sometimes meddle in his relationship with Chizuru.
Okata (御方, Okata)
- Main article: Okata
- Okata is a yokai who is the head of the Sahara family; her true form is that of an old woman. She has survived for thousands of years.
Kunpō High School Staff
Iku Sahara (砂原 幾, Sahara Iku)
- Main article: Iku Sahara
- Voiced by: Noriko Shitaya (Japanese), Karen Strassman (English)
- Iku is a social studies teacher and is Kouta's homeroom teacher. She is prone to making silly mistakes and is very childish. She is in fact possessed by a yōkai and thus has dissociative identity disorder as an effect. She has to conceal her true identity to Chizuru, and oversees the spirits at school.
Takao Yatsuka (八束 たかお, Yatsuka Takao)
- Main article: Takao Yatsuka
- Voiced by: Takashi Matsuyama (Japanese), Dan Woren (English)
- Takao is the gym teacher at Kouta's school, and has a scary face. Like Iku, he too is overseeing the spirits at school. He is very wise, and gets along with Yukihana.
Yukihana (雪花, Yukino Hanadai)
- Main article: Yukihana
- Voiced by: Risa Hayamizu (Japanese), Tara Platt (English)
- Yukihana, a yuki-onna, makes her first appearance in volume three of the novels. She is a ninja who works under Tamamo at her hot-spring hotel. She has a honest personality.
In volume seven of the novels, she becomes a teacher for the handicapped at Kouta's school. When working as a teacher, she goes by the name Hanadai Yukino (雪野花代, Yukino Hanadai), and if someone calls out to her using the name Yukihana, she will say she is not that person. She can manipulate snow storms and uses a gleaming sword in battle, and is physically very strong. Her name means Snow Flower.