Kyôya Oiranzaka is an oni who formerly served as the commander of the support squad in the Kyoto branch of the Oni Organization, an institution that opposes the Momotarou Clan. Following his time as a field commander, he took on the role of school doctor at Racchu Academy, where he continues to provide medical care and support to other oni. He is a rare healer-type oni whose abilities center on his blood, which possesses extraordinary regenerative properties. By exposing injured allies to his blood, he can vastly amplify their natural recovery, even regrowing lost limbs such as hands or feet. However, administering too much blood at once can cause the recipient to develop antibodies, limiting the extent of regeneration possible in a single treatment. He can also heal himself by bathing in his own blood, a resourcefulness that has allowed him to survive life-threatening wounds, including having his carotid artery severed in combat. Despite lacking significant frontline combat ability, his presence on the battlefield is considered invaluable because he can keep severely injured fighters alive and operational. Oiranzaka presents himself with a flamboyant and flirtatious demeanor, often coming across as a playboy who teases those around him. This casual exterior, however, masks a deeply sincere and conscientious personality. He takes his responsibilities seriously and is driven by a firm conviction that the role of the support unit is just as vital as that of the front-line fighters. He believes that those who fight on the front lines can only do so because someone is protecting their backs, and he is willing to push himself to exhaustion to keep his comrades from dying. His determination is encapsulated in his vow that as long as he is present, he will not allow anyone's future to be taken away. A notable quirk is that he becomes excessively affectionate and prone to kissing when drunk, though he restrains this behavior around one of his closest friends. His key relationships include a deep bond with Mudano Naito, his former classmate from Racchu Academy with whom he shares a long history and mutual trust. He also has strong ties to other former classmates, including Masumi Yodogawa, and he commands the respect and gratitude of many younger oni whom he has healed and supported. Over the course of the story, Oiranzaka transitions from a capable but somewhat understated support leader into a figure who willingly endures great personal cost to protect the next generation of oni. He endures a near-fatal ambush by Tsubakiri Momomiya, a member of the Momotarou Clan, and survives by drinking his own gushing blood. Later, during the Nerima arc, he exhausts himself to treat multiple critically wounded allies, appearing haggard afterward but unwavering in his commitment. His development is marked by an increasing willingness to sacrifice his own well-being to fulfill his role as the linchpin of the oni forces' survival. Physically, Oiranzaka is a tall man in his early thirties with tousled red hair, sharp red eyes, and distinctive moles beneath both eyes and on his lower lip. His fashion sense is stylish and slightly punk-inspired, featuring a white coat worn over casual clothes, black nail polish, multiple piercings, and rings.