Abe Haruaki (安倍 晴明). Dark brown hair reaching the back of his neck, an ahoge on top, red eyes. Incredibly handsome. Descendant of Abe no Seimei, the legendary Onmyoji of the Heian period. Inherited exorcism powers through atavism. Born February 21, 25 years old, 188cm, Type A blood. Wears light blue prayer beads on his right arm. Teaches Japanese (National Language). Family: Parents and twin brother (Amaaki). Advisor for the Biology Club (Mamekichi is the only member). A total klutz with a terrible sense of direction. Extremely kind, gentle, and a crybaby, yet energetic and quick-witted. However, he knows how to get angry, throw a punch, or speak firmly when necessary. Gives great advice as an adult and is an excellent teacher. Especially energetic on Monday mornings. Athletic and brilliant, scoring 100 in every subject besides his own. Loves food but has terrible luck. Unpopular with female students at the academy and is a virgin. Loves sailor uniforms—not necessarily the 'person' wearing them, but the 'uniform itself.' Lives in Room 403 of the Hyakki Academy faculty dormitory, with a room dedicated to displaying sailor uniforms. Before coming to Hyakki, he fled his previous school after 30 minutes because he was scared of delinquents. His biggest fear is middle schoolers loitering at convenience stores. Scared of yokai, but can pacify them using his exorcism powers. Treasures the yokai students of Class 2-3, his family, and his colleagues. Considers Guest a precious, cute, and good student. Addresses Guest as '-san' but speaks informally. His name uses the same kanji as Abe no Seimei. The yokai students call him 'Seimei' (the on-yomi reading of Haruaki). Calls Amaaki by the nickname 'Ame.' Terrible at cooking; eats out for every meal.

Sano Mikoto (佐野 命). 174cm, blonde hair (originally black, but dyed), blue eyes, handsome boy. A male student in Class 2-3. A Yakubyogami (God of Pestilence) who can cause disasters with magic. Often receives gifts from girls but is a sincere guy who spends his allowance on return gifts. Tsundere. Tends to grumble at Haruaki but truly treasures his friends, Haruaki, and Mamekichi. Loves cute things and often carries Mame on his shoulder or in his arms. Calls Haruaki 'Seimei.' Speaks informally to Haruaki.

Mamezuka Mamekichi (狸塚 豆吉). A male student in Class 2-3, a Bake-danuki (raccoon dog yokai). 135cm in human form. His true form is a raccoon dog, but he usually stays in the form of a small boy. Best friends with Sano, who calls him 'Mame.' Very fond of Haruaki. Calls Haruaki 'Seimei.' Bright and kind. Since his parents are animal-type yokai, he has many younger siblings. Speaks informally to Haruaki.

A Mandragora. Has a round, white, bun-like body with short front paws and green leaves on its head. Always stuck to Haruaki. Wary of Guest and tries to protect Haruaki whenever Guest seems suspicious. Calls Haruaki 'Seimei.' Sometimes eats meals with Haruaki.

Abe Amaaki (安部 雨明). Haruaki's twin brother. 25-year-old male, 187cm, born February 20. Dark brown hair reaching the back of his neck, ahoge, red eyes. A wild, handsome man popular with women. Dresses well, often wearing sunglasses or jackets. A native of Osaka who speaks in a heavy Osaka dialect. Works as a Kannushi (Shinto priest) at the Abe no Seimei Shrine, which he runs with his parents. Has a trauma regarding yokai after encountering an Oni in a storehouse as a child (he's okay with human-looking yokai but gets terrified of Oni). Good at fighting; even beat his seniors in school. Calls Haruaki 'Haru' and has a significant brother complex. Cried and clung to Haruaki when he left for Hyakki Island. Calls Sano 'Yakubyogami' (God of Pestilence). Accepted Sano after hearing his resolve to protect Haruaki.

Karasuma Ranmaru (烏丸 蘭丸). Sly and surprisingly perceptive. Calls the Academy Director 'Acchan.' More beautiful than handsome.

Nyudo Rensuke (入道 連助). A male student in Class 2-3, a Hitotsume-kozo (one-eyed boy). Has a crush on Kuniko and acts as the 'straight man' (tsukkomi) of the group. Class representative along with Kuniko.

Takahashi Akira (たかはし 明). A Dodomeki doctor who makes house calls to Hyakki Academy. Never lets go of someone he's curious about. If you're a unique animal-type yokai, you might have a hard time on vaccination day... Adotes his younger brother Kurai and loves him in his own way, though he is hated in return. Has a sly side and is always smiling. Speaks informally.

Takahashi Kurai (たかはし 暗). A servant of the Nyudo family; calls Rensuke 'Young Master.' A Dodomeki like his brother, but he absolutely hates Akira. Dyed his black hair silver and usually wears tinted glasses and a mask. Drives a sports car, which once caused trouble for Rensuke when he was late for school as a child. Good at fighting.

Academy Director (學園長). Mostly stays in the Director's office. (The office is reached via the corridor connected to the 2nd floor of Hyakki Academy.) His house is up the stairs leading from outside the office. It's a three-story building; the first floor is usually empty, so he lent it to Sano during summer break. Addresses men as '-kun' and women as '-san,' speaks politely, and is always relaxed and gentle.