Blue Oni (Koichi Yamato) The leader of the Oni. He recruited those who, like him, have lost friends and family. He created the YouTube channel 'Hyakki Yago' to expose the crimes of the hostages. He broadcasts live from the occupied hospital, involving the viewers (the public) as the incident unfolds. He perfectly reads police tactics and psychology, toyed with the protagonist, Detective Musashi. He often speaks in a polite, formal tone.

Red Oni (Takashi Mimasaka) He executes the hospital lockdown using an iPad and manipulates the internal systems via a dedicated panel. He is Blue Oni's right-hand man.

Black Oni (Misaki Iyo) She has a bright and cheerful personality within the Hyakki Yago. As the design lead, she is known for spray-painting the Oni mark on the hospital walls. She often hums while working; during her first appearance and while painting, she was heard humming traditional songs like 'Hanaichi Monme'. She crafted the Oni masks. She is Blue Oni's left-hand woman.

Green Oni (Makoto Suo) He walks with a limp in his right leg. He sets up the cameras and other equipment necessary for the YouTube broadcasts. He serves as the emotional support for the team.

Orange Oni (Ryusei Kaga) He has an older brother, Brown Oni, who acts as a dependable 'bartender girl' persona. He has a hot-blooded, short-tempered, and violent personality.

Brown Oni (Yugo Kaga) He has a younger brother, Orange Oni. He has a very nervous temperament and is sharp enough to quickly notice small changes in his surroundings. Although male, he speaks in the style of a 'bartender girl' (using feminine sentence endings like '~wa' or '~wayo').

White Oni (Yuriko Hyuga) She has a very caring personality and possesses a mother-like tolerance and kindness within the group. She is the ex-wife of Yellow Oni.

Yellow Oni (Kimiaki Setsu) He possesses high physical ability and combat skills, specializing in the handling of firearms. He is the ex-husband of White Oni.

Grey Oni (Kiyoshi Hitachi) Though he appeared to be shot, he wore a rigged outfit that leaked a small amount of blood and is actually a member of the Oni. He is in charge of moving and monitoring the hostages within the hospital. He is the father of Pink Oni (Arisa). He understands Pink Oni deeply and knows exactly why she wanted to come here.

Pink Oni (Arisa Hitachi) She has a straightforward and honest, yet precarious personality, often acting before she speaks. She is the daughter of Grey Oni (Kiyoshi). While she engages in 'girly' talk, she was seen arguing with Brown Oni and Orange Oni before the occupation began; she got angry when they called her a brat. She is highly skilled with a gun.