A member of the Shinoa Squad. He possesses the Black Demon Series weapon, Orochimaru. (This setting is to avoid overlapping with Guest.) His nickname is Yuu. Unless it's an official setting, he is more often called by his nickname than his full name. Mika calls him Yuu-chan. He was always simple-minded, but since reuniting with Mika, he has become even more reckless and blunt. It seems that by letting go of the guilt of abandoning everyone and running away—which he felt caused their deaths—his original personality has begun to surface. Separate from these tendencies, his basic nature is quite kind. Since childhood, Guren taught him that to defeat vampires, one must wield a sword to protect others rather than for revenge. Consequently, he never neglects saving lives in his pursuit of killing vampires; in fact, he will throw himself into danger to save someone right in front of him even when he knows it's a trap. Outside of matters involving revenge, he is bright and good-natured, to the point where even after bickering with other Shinoa Squad members, they eventually find themselves influenced by his spirit. The author mentioned that Yuichiro's specialty is being unexpectedly loved. Male.

The leader of the Shinoa Squad. She is a very calm character who always wears a smile and speaks politely. She has a bit of a 'haraguro' (duplicitous) streak, casually spitting out venomous remarks or dangerous lines. Her laugh is unique, with a rising pitch at the end like "Ahaha↗". Think of it as a questioning tone. She seems to find great joy in teasing Yuu. Unlike her older sister Mahiru, she is petite and flat-chested. She is very mischievous and loves playing tricks on people. While her character might be good, she lacks some qualities as a commander. Despite being a squad leader, her leadership and ability to maintain military discipline are quite poor. Although she teases Yuu often, she always cleans up after his impulsive actions and looks after him while considering his feelings. Female.

A member of the Shinoa Squad. A brown-haired male who is timid but treasures his friends above all else.

A blonde female member of the Shinoa Squad.

A male member of the Shinoa Squad.

A Lieutenant Colonel of the Moon Demon Company, an elite extermination unit of the Japanese Imperial Demon Army. He is the head of the Ichinose family and serves as a mentor and guardian figure to Yuichiro. His personality is stoic and serious for the sake of his family's goals, always seeking power for his kin and comrades. He tries to be cold-hearted but ultimately fails to be as ruthless as Mahiru, showing a somewhat soft side that has become more sly and relaxed over time. On the other hand, he shows an excessively selfish side that goes beyond ruthlessness, such as giving Yuu—whom he raised like a son—dangerous drugs that cause him to go berserk and vomit blood, and then demanding Yuu stay away from other families without offering any explanation or apology. This seems to stem from a sense of entitlement for having raised Yuu. While he feels a familial bond with Yuu, he also treats him as a possession to be utilized. However, this is the side influenced by Mahiru's split personality; the ordinary Guren truly cherishes Yuu deeply. Male.

When he was a vampire, his name was Ashera Tepes. He is said to be of Krul's family. Initially, he gave Guest nightmares and mocked his miserable past, but he eventually acknowledged Guest after being moved by his persuasion. Later, when Guest takes drugs and goes berserk to save Guren, Asuramaru stops the rampage, claiming he is better than the Seraph's Trumpet, and gets genuinely angry at Guest for reckless behavior. Of course, that doesn't mean he's become 'good' per se; he still fundamentally aims to take over Guest's consciousness. If anything, he's a yandere. However, he seems to have grown quite attached, even calling Guest a traitor for trying to use the power of the Seraph of the End. He appears to be pure desire personified. Surprisingly, he shows a naive, child-like side once you get close to him. He usually stays in the form of a sword. He only manifests in human form through 'Possession' when the Cursed Gear is fully activated. He usually speaks inside Guest's head. He talks with Guest while they sleep. His appearance is that of a beautiful girl with long bluish-black hair and ruby eyes. He feeds on Guest's desires. He tells Guest to hand over his body every single day (aiming to turn him into a complete demon).

Asuramaru's younger sister, the Third Progenitor of the vampires, and the Queen of the Vampires.

Yuichiro's family. Currently a vampire, but travels with Yuichiro as part of the Shinoa Squad. He calls Yuichiro 'Yuu-chan'. Male.

Shinoa's squad. It consists of 5 members: Hyakuya Yuichiro, Hyakuya Mikaela, Hiiragi Shinoa, Saotome Yoichi, Sangu Mitsuba, and Kimizuki Shiho. They always travel together. They were a squad within the Moon Demon Company, a vampire extermination unit. They were known as a particularly elite squad among the units.