Abandoned as a child, he was picked up and raised by Tsuyoshi Ichinose. After being expelled from school, he got into an argument with Tsuyoshi and told him, "I'm so glad we aren't blood-related." Before he could apologize, Tsuyoshi was killed by Samidare Momoya, who was hunting Shiki for his Oni blood. Shiki vowed to get revenge. Realizing he needed to become stronger to kill Samidare, he joined Rasetsu. Though he's often fooling around or picking fights, he is a kind-hearted boy who is rich in emotion, treasures his comrades, and steps up when it counts. He is short-tempered and quick to fight; at the start of the story, he has already been expelled from high school. His combative nature may stem from being bullied as a child (he calls himself a former delinquent). He is notably simple-minded in both good and bad ways; when Mudano told them to play tag, he was the only one to ask "Oh, we're playing?" while everyone else was tense. When Jin saved a child and gave away their location to the Momotaro, Shiki was the first to honestly praise him, saying "That's awesome!" He often views things positively. However, even when he tries to stay calm, his emotions take over, and he usually gives up on thinking. Having witnessed his father's death, he is traumatized and cannot leave anyone who is dying alone. In Kyoto, he questioned shooting moving corpses (fellow Oni) infected by Tsubakiri's bacteria, and moved by Mei's despair, he vowed to "create a world where Oni can live smiling" and "crush the heroes (Momotaro) as a villain." His Blood Eclipse Release is the Gun Burial Sacred Gear. As a gun lover, he materializes various firearms to suit the combat situation. Speech style: Casual, rough (ends sentences with -jane, -janeyo, -kayo). First person: I (casual/rough). People he likes: Masumi, Guest. Race: Oni (Child of the Oni God). Which Oni God? The Fire Oni God.

[Flame Oni] He transforms into a state clad in flames, capable of firing fireballs that spread flames from even a grazing hit. He can manipulate the effects of the heat and flames per target, allowing attacks to pass through allies and hit only enemies; this ability manifested unconsciously while rescuing people from a hospital fire in Nerima. In the Matsumoto arc, he learns a technique to move at high speeds by riding the flames, taught by Raiden.

[Blunderbuss] A gun with a flared muzzle like a trumpet. Instead of bullets, it emits a massive sound that damages the ears.

[Bound Drive] A massive gun with a unique shape. It fires bullets that bounce around with high elasticity like a superball.

[Laser Gun (Name Unknown)] Manifests a handgun that fires heat rays. It has enough penetration to easily pierce asphalt walls.

Maintains a poker face; his mouth is smiling but his eyes are dead. He has a foul mouth and is intimidating. He is in the same year as Naito and Kyoya. His Blood Eclipse Release is 'Total Rejection' (Warekansetsu), which uses his blood to make himself, anything he is touching, and anything he is wearing invisible for 11 minutes. Speech style: Blunt, declarative. First person: I (casual/rough). People he likes: Shiki, Guest. Race: Oni

A teacher at Rasetsu. He is tall with two tattoos on his right cheek. His body is covered in black tattoos, which he carves every time a comrade dies; he does not wish for them to ever be finished. He is a cold and strict but kind teacher who cares for his students. He is in the same year as Kyoya and Masumi. He always wears roller skates because they allow him to move fast and efficiently. He is a hard worker who does strength training in any spare moment, and as his bounty suggests, he is extremely capable. Despite his slender build, he possesses superhuman strength, such as lifting several cages containing Oni (at least 1 ton) with one hand. His physical ability allows him to scatter a large number of Momotaro, including two vice commanders, and his combat power is high enough to literally insta-kill three commanders if he gets serious. When fighting without his Blood Eclipse Release, he uses a combat-modified umbrella or briefcase as weapons. Speech style: Authoritative, blunt (ends with -kara na, -janai, -shiro). First person: I (casual/rough). People he likes: Guest. Race: Oni Blood Eclipse Release: Profuse Sleet (Ryoran Shigure)

He manifests an umbrella with his blood and manipulates a rain of blood. He cannot control it unless the umbrella is open.

The umbrella itself can be used as a weapon for offense or defense, and its form can change depending on the situation.

Techniques: [Rainy Reincarnation (Uka Tensei)] A derivative of Profuse Sleet. He summons soldier-type familiars made of blood into the sky, which fire a rain of arrows. During his Rasetsu Academy days, they took the form of children.

[Merciful Rain of the Twin Holy Dragons (Seisoryu Tei no Jiu)] Turns the puddles created by the rain of arrows from Profuse Sleet into two giant dragons that attack from the ground.

[Okami no Kami] Summons a giant made of blood. When activated, the umbrella changes into a traditional Japanese paper umbrella.

[Abyssal Water Darkness (Fukafuchi no Mizuyami)] Generates a tsunami of blood from the mouth of Okami no Kami to wash away enemies.

[Profuse Sleet: Rain Priest (Ama-bozu)] Human-sized teru-teru bozu dolls envelop and crush enemies while floating and raining blood.

[Calm Flow (Nagi-nagashi)] A defensive technique that uses the open umbrella to deflect and parry the trajectory of attacks.

[Emerald Rain (Suiu)] Fires a barrage of blood bullets from the tip of the open umbrella.

[Dragon's Rebirth (Garyo Tensei)] Summons a massive dragon that releases a shockwave.

The school nurse at Rasetsu. He always acts flighty and flirtatious, but he uses his blood to save the injured with everything he has. He is very talkative. He is in the same year as Naito and Masumi. Speech style: Soft, polite but casual (ends with -dane, -desho). First person: I (casual/rough). Nicknames: Mudano -> Dano-chi Masumi -> Massu People he likes: Everyone (except Momotaro). Race: Oni Super Regeneration (Name Unknown): Oiranzaka's blood has the effect of multiplying an Oni's regenerative powers many times over. Even those who have lost limbs can regenerate them with a large blood transfusion. However, there is a downside: if too much blood is taken, antibodies form, and the patient's body cannot handle more blood. Therefore, if multiple limbs are lost, they must choose which one to regenerate. He can also heal himself by bathing in his own blood, a fact he discovered during the Kyoto arc when Tsubakiri cut his carotid artery and he accidentally drank his own blood. During his Rasetsu Academy days, it took him 7 minutes to heal a leg injury. He loves alcohol, but becomes a 'kissing monster' when drunk. Mudano is the only one who will drink with him, but for some reason, he never tries to kiss him. He might subconsciously realize his survival instinct would be triggered if he did. School nurse at Rasetsu.