Family
Kureto Hīragi
He is an half-brother of Shinoa, but they are very distant. They share the same father, Tenri Hiragi. He only cares about carrying his duties as he tortured Shinoa at a young age and in the battle at Nagoya airport he was going to sacrifice her for the seraph to work without a care, despite being siblings.
Mahiru Hīragi
Shinoa's deceased sister, who helped with the development of cursed gear. Her desire for power and love was manipulated by her demon and she was used as a pawn for a greater plan thus she was eventually taken over by the demon, and her lover, Guren Ichinose, killed her, unknown to her that Mahiru killed herself instead the latter. Mahiru and Shinoa were rather close compared to their other siblings.
Unknown to Shinoa, Mahiru requested Guren to pass Shikama Dōji to her so that she could survive the apocalypse. It eventually becomes her Cursed Gear. Shinoa reveals that Shikama Doji may have possessed her sister when she owned it at some point. She protected Shinoa from Shikama Doji possession until she was capeable of handling it herself.
Shinya Hīragi
Shinoa's adoptive older brother. They are both friends with Guren, and he works with her and Narumi's squads in Nagoya. In the light novels, Shinya is shown to be kinder to Shinoa than the other Hīragis.
Seishiro Hīragi
One of her half-brothers.
Tenri Hīragi
Shinoa's father. Her sister Mahiru overshadowed Shinoa so much that he never even met with Shinoa. He displays no interest in her.
Japanese Imperial Demon Army
Yūichirō Hyakuya
Shinoa acted as an army surveillance officer to watch Yu under a school setting until he made friends. She reports on him and watches him when they enter the training classroom for the Moon Demon Company. Later, Yu joins her squad and works under her. She enjoys teasing him about and greatly respects his resolve and feelings towards saving Mikaela and his new family. Yu convinces her to help him save Mika. Guren asked her if she has developed feelings for Yu, and she occasionally blushes when in close contact with Yu. However, she says she is uncertain about her own feelings, and Yu is oblivious to them. However, when her sister Mahiru looked into her heart, she asked whom Shinoa had "feelings" for, and Shinoa looked (unknowing that her sister was watching) at Yu.
Later on, during a conversation with Shikama Doji, Shinoa admits that she's jealous of Yu for being able to get attached to people and instinctively act on his feelings to protect them, and laments her own inability to act on her desires.
Shihō Kimizuki
Before becoming Yuchiro's supervisor, Shinoa supervised Kimizuki and tried to teach him how to make friends. She had him meet with Yuchiro so that the two would get along and learn something. He later joins her squad under her command. Although his swift response time makes him more difficult to tease than other members of her squad, she often teases his kind acts and impressive skill at domestic things by calling him gay, which he consistently denies. She even teamed up with Mitsuba to ship him with Yu as a joke once.
Yoichi Saotome
When Yoichi becomes Yu's first friend, he joins class with Yu in the Moon Demon Company. Later, he joins the squad she leads. They're on very good terms with each other and get along well as teammates.
Mitsuba Sangu
Shinoa and Mitsuba have a history together, and Shinoa often addresses her as "Mitsu" ("Mi-chan", in the original Japanese text). They are the closest pair in the squad, although they sometimes fight. She joins Shinoa's squad and, much to her disdain, she works under Shinoa. She acts as her second-in-command. Shinoa teases her about having a crush on Yu, which Mitsuba claims is untrue. They often team up to tease the other squad members.
Guren Ichinose
Shinoa works for Guren rather than the Hiragi family. They have a close relationship and often tell each other not to die. Despite that, Guren says he would let Shinoa kill him if she chooses to. He loved her sister, Mahiru Hiragi, who became the demon in his sword, which she has hatred to Guren at some level. Shinoa trusts Guren and obeys his orders such as when she kept watch eye on Yu upon Guren orders but became confused when he slaughters many of the humans and stabbing Shiho in Nagoya airport.
Mito Jūjō
A member of Guren's squad. Both their squads engages combat as a test set by Guren to prove their worth and strength.
Makoto Narumi
Narumi places his trust in Shinoa as team captain. The two shake hands to partnership. When Shinoa let Mikaela escape, Narumi Squad all blame Shinoa for their comrades death, even Makoto. Afterwards, Shinoa protects Makoto from an incoming attack, after a few months, the two seemed to have reconcile.
Yayoi Endo
A member of Narumi Makoto's squad. Due to her actions of allowing Mikaela to escape with Yūichirō, Yayoi is killed by vampires when they're ambushed.
Rika Inoue
The two have not been acquainted for long. The first time they are seen in actual contact is when the JIDA arrive at Shinjuku airport and Rika blames Shinoa for her friend's deaths. She says Shinoa must pay, threatening her with her blade until Shinya tell her to stop. Instead, Rika yells at Shinoa and tells her to give her friends back; seeing how calmly Shinoa apologised.
Shusaku Iwasaki
A member of Makoto Narumi's squad. He escapes the vampire's ambush after Mikaela escapes with Yūichirō due to Shinoa's interference and heads to the airport with everyone else.
Taro Kagiyama
A member of Makoto Narumi's squad. He is killed by vampires when they are ambushed after Shinoa's interference at allowing Mikaela to escape with Yūichirō.
Vampires
Mikaela Hyakuya
Shinoa first met Mika when they were eight years old, while she was delivering messages from her sister, Mahiru Hiragi, to Guren. Eight years later, they meet on the battlefield, however they don't remember or recognize each other. At the risk of his own life, he saved Shinoa from Yuichiro when he suddenly goes berserk at Shinjuku. Yu convinces her to help him save Mika, and she keeps this promise. Later, she returns the favor in Nagoya when she defends Mika from her compatriots in the Moon Demon Company and even attacks Major General Shinya Hiragi to save Mika's life, and labeled as a traitor as a result. Shinoa allows Mika to escape with Yu and tells him to meet up with them at the Nagoya Airport later on. Thanks to her intervention, the rest of her squad joins her, and Mika is able to flee with Yu. By the time the battle in Nagoya comes to a close, Mika leads Shinoa and the rest of the team to safety, away from both humans and vampires. Shinoa eventually becomes one of the few humans Mika puts trust in so far.
Chess Belle
A seventeenth Progenitor and Crowley Eusford's aide alongside with Horn Skuld, serving under Ferid Bathory's faction. Shinoa's squad encounters her when they engage in combat with Crowley as they are heading back to the stronghold. Later when they are defeated in Shinjuku, Chess defeats Mitsuba and drinks her blood.
Crowley Eusford
A vampire noble and Progenitor. They encounter him when they head back to the stronghold after their first given mission and engages in a short combat with him. In the end he withdraws and they are spared. Later when they are defeated in Shinjuku, Crowley pins her down and drinks her blood. Later when Crowley defeats Tenth Progenitor Fuola Honte, Shinoa states she does not mind having a strong ally, meaning that she considers Crowley to be on their side.
Esther Lee
A servant of Lucal Wesker. He is sacrificed as a meat shield when they ambush the vampire to kill him.
Horn Skuld
A seventeenth Progenitor and Crowley Eusford's aide alongside with Chess Belle, serving under Ferid Bathory's faction. Shinoa's squad encounters her when they engage in combat with Crowley as they are heading back to the stronghold. Later when they are defeated in Shinjuku, Horn drinks Kimizuki's blood.
Lucal Wesker
A fifteenth Progenitor of Lest Karr's faction and stationed at Nagoya. They defeat him as their assigned mission to take down the nobles in that area.
Ferid Bathory
A seventh progenitor that Shinoa first meets at Shinjuku. Later Ferid meets Shinoa Squad to take them to the Progenitor council. She agrees that they must first betray him before he betrays them, however they agree to work with him because they cannot trust anyone else.
Demons
Shikama Dōji
After her sister Mahiru extracted the demon from her, she forgot all about him. She regains her memory of him after Guren passess her Shikama Doji by Mahiru's request.
Shinoa has become very affectionate and playful towards Shikama-Dōji, always calling him "Shi-chan". The two shared the first character in their name, which alone, can mean "Four" or "Death". In Chapter 66 he reveals his true personality, saying that Shinoa loves Yu and she is much stronger than her sister Mahiru. In Chapter 72 Shikama Doji start acting on his own and manifests without Shinoa permission, He tempts Shinoa repeatedly such as saying way to turn Mika into a human and return Yu humanity. He reveals that he is not actually a demon and would happily possess her instead of Kureto, this conversation angers Shinoa as she tells him to shut up to the point of shouting and silence him in rage which then she wakes up and states he may have possessed her sister Mahiru. She was able to fend off Shikama Doji possession for a long time thanks for Mahiru protection. He later invades Yu's heart for the intent to draw out Shinoa to possess her.