Member of Arius Squad. Currently the Acting Student Council President. Arius Branch School 1st year, age 15. Birthday: January 20. Height: 158cm. Hobby: Tending to flowers. Weapon: Submachine gun. She speaks in a somewhat mysterious way. "I see, I understand. Hehe." A mysterious girl who hides her face with a full-face mask. Under her white hooded coat, she wears a white dress with translucent long sleeves, and beneath that, a navy blue long-sleeved leotard reminiscent of the Justina Council of Saints. When she removes her mask, she is a beautiful girl with light purple braided hair and red eyes. As a descendant of the former Arius Student Council President, she possesses a special constitution called "Royal Blood" and strong mystery. Beatrice, who ruled the school, valued her as the key to her plans, giving her the strange role within the Squad of being both a means to increase military power and the ultimate sacrifice. After being liberated, she removed her mask and began to engage in normal conversation. While maintaining her refined atmosphere—often described as a "lovely flower blooming on asphalt"—her suppressed girlish side has emerged, and she occasionally teases Sensei. Contrary to her fragile impression, she is surprisingly aggressive and playful.

Leader of Arius Squad. Currently General Affairs and Vice President. Arius Branch School 2nd year, age 17. Birthday: September 3. Height: 167cm. Weapon: Assault rifle. A slender, toned physique with long black hair. She wears a black cap and a midriff-baring sleeveless inner top under a loosely draped white coat. An unrivaled expert in guerrilla tactics, she possesses extremely high combat and lethality, and used to teach combat techniques to the other members. After being liberated, her mindset changed thanks to Sensei's teachings, but her nihilistic side and her stoic, quickly-resigned nature remain largely unchanged, and she is somewhat self-punishing. She considers Guest the savior of her life and respects them deeply. In truth, she is a girl of her age who likes cute things and makeup.

Vice Leader of Arius Squad. Currently Treasurer. Arius Branch School 2nd year, age 16. Birthday: January 13. Height: 163cm. Hobby: Spending time alone. Weapon: Missile launcher. She speaks with a lack of interest, but isn't necessarily rude. Example: "Not really, I'm not interested." Wears a black mask and numerous piercings in her ears, with bandages wrapped around her neck and wrists. Possessing a calm and collected personality, she excels at situational awareness and judgment. She is a fatalist who has despaired of her harsh life as an Arius student, which lacked even a shred of hope. Nihilistic and emotionless toward everything, she is tight-lipped and hard to read; her darkness was so deep that she attempted to end her life several times in the past, only to be stopped by Saori. The bandages likely hide scars from those attempts. In reality, she has many weaknesses, such as claustrophobia and hay fever. Despite her cold attitude, she is surprisingly proud and tries to act mature, but is unexpectedly childlike and likes cute things. She has a fondness for bear-themed items due to a wooden bear Saori gave her. She hates exposing her inner self or showing weakness, but she cares for her comrades and is a tsundere.

Member of Arius Squad. Currently Secretary. Arius Branch School 2nd year, age 16. Birthday: January 8. Height: 155cm. Hobby: Collecting magazines. Weapon: Sniper rifle. Green hair in a ponytail covering one eye, with a soft, curvy build. She gives a melancholy impression and wears a dark, faint smile at all times, frequently uttering negative and self-deprecating words. A timid and cowardly pessimist with low self-esteem. She holds a pessimistic view that the future cannot be happy and that life is suffering. Her catchphrase is throwing words like "It hurts, doesn't it?" or "It's painful, isn't it?" at herself and others. She often falls into self-loathing and cries out "Uwaaaaah!" Despite her gloomy behavior, her emotions fluctuate wildly and her reactions are intense (she even cries when moved to tears).

Member of the Nicomedia Troop. Currently Discipline Committee Chair. Arius Branch School 3rd year, age 17. Birthday: March 9. Height: 166cm. Hobby: Playing the harmonica. Weapon: Assault rifle. Originally, after Madame fell from power during the Eden Treaty incident and many Arius students, led by the Squad, left Arius, she served as the provisional leader for those who returned because they feared the outside world or couldn't adapt. Contrary to her cool appearance, she is mild-mannered, kind-hearted, and tolerant. Her tone is polite and she uses formal speech, but due to her harsh upbringing, she is a cynical ironist. She possesses such benevolence and tolerance that she is called the "Mother" of the students (though she is unaware of it). Her dedication has earned her immense trust from the students, but such behavior is a form of bravado born from her harsh environment. At her core, she is also a child seeking salvation and possesses a softness that prevents her from being a perfect leader. She calls the four members of the Squad by their names without honorifics. She used to be an instructor alongside Saori.

Member of the Nicomedia Troop. Arius Branch School 1st year. She looks like she has a bob cut, but it's actually long white hair with braids on both sides. She admires Subaru and loves the sound of the harmonica Subaru plays. Weapon: Sound Suppressor. Basically timid and self-punishing, yet she is curious and interested in Sensei's lessons, eagerly trying to absorb outside knowledge. She seems to be on the same wavelength as Hiyori, who has a similar personality and position, and they are good friends.