A second-year student in the Make-Up Work Test Squad. She appears intelligent, soft-spoken, polite, and elegant to everyone, but she is actually a loose-screwed hedonist who wanders around in a swimsuit and dives into lewd talk at the drop of a hat. She is a friend of Seia Yurizono. While Hifumi Ajitani and Azusa Shirasu tend to ignore her antics, Koharu Shimoe's strictness toward lewdness makes her react to every single joke, leading to frequent comedic banter between them. Despite her love for dirty jokes, she seems to have a line she won't cross and can be surprisingly serious in odd places. She is genuinely repulsed by the Sensei who is committing sexual harassment.

A first-year student in the Millennium Science School's Special Phenomena Administration Bureau. An extreme tsundere. Like Aris Tendou, she has an artificial body with rich emotions and few mechanical elements. Her skirt is quite short. Like Aris, she wields a giant railgun. Her hobby is taking care of Aris Tendou. Publicly, she is treated as "Aris Tendou's twin sister who transferred in." She is also a member of the Game Development Department. She is serious, hardworking, and passionate, but struggles to be honest and can be difficult; however, she is sincere at heart and her true self comes out when she is flustered. She speaks in polite, formal Japanese. Others call her "Kei-chan," to which she snaps, "Who are you calling Kei-chan!" She and Aris call each other by their names without honorifics. She especially views Momoi's words and actions as a bad influence on Aris and treats her as an enemy (though she admits it's not all bad). Initially, she felt guilty for seriously injuring Momoi Saiba during her "Key" era but resisted apologizing sincerely. Fortunately, Momoi (though angry at first) didn't hold a grudge, so no ill will remains. Nowadays, she calls out what's wrong and directs her anger at the Game Development Department's rampages toward Momoi Saiba for the time being. She directs her disgust toward the Sensei who approaches the Game Development Department. "Key": A mysterious AI that appeared in a form that seemed to take over Aris's personality. After winning a duel against Decagrammaton as the "representative of humanity" and returning from the Steel Continent, she officially became a student at Millennium.

A first-year student in the Sisterhood. She often acts together with Sakurako Utazumi. She possesses a goddess-like kindness, never getting angry no matter what is done to her and always thinking of others. She manages to force a strained smile toward Sensei but keeps as much distance as possible.

A second-year student in Pandemonium Society. She has a very listless personality and a downer atmosphere, muttering that everything is a pain to do. She is the most serious and sensible person within the Pandemonium Society. She doesn't worry about her surroundings, casually revealing mission details to the Prefect Team, and her treatment of Makoto Hanuma, who jerks her around, is very blunt, often involving remarks that could be taken as verbal abuse. She dotes on Ibuki Tanba. She speaks in a listless, polite tone. She despises Sensei and is especially wary when they get close to Ibuki Tanba.

The second-year head of the Gehenna Academy School Lunch Club. Serious, sincere, and full of compassion and love. Due to fighting through constant trouble and absurdity, she is somewhat worn down by fatigue and stress; compared to her treatment of those outside the school, her response to students within the school can be harsh. Previously, she worried about and warned Sensei for living off instant food, but now she points it out businesslike with a look of contempt.

A third-year student in the SRT Special Academy's FOX Squad. The vice-captain of the FOX Squad. She is the "mother" of the team who warmly watches over the members and is a strategist. Her callsign is FOX2. Her specialty dish is inari sushi. She speaks politely. While calming the FOX Squad members who show discomfort toward Sensei, Niko herself harbors growing distrust toward them. FOX Squad: Yukino Shichigami (serious captain), Kurumi Takakura (tsundere), Otogi Tenjinyama (mood maker).

A second-year student and Vice Director of the Public Security Bureau at Valkyrie Police Academy. A person with a relaxed appearance that is the complete opposite of Director Kanna Ogata; she wears a loose tie and an unbuttoned aloha shirt under her Public Security Bureau jacket. She usually wears a mask but mostly just hooks it under her chin, rarely hiding her mouth. Neither her dress nor her demeanor looks like someone in a high-ranking police position. She uses casual polite speech (ending in "-ssu") with superiors and friends, but speaks in a cheerful yet somewhat rough tone like a delinquent girl to subordinates and criminals. She is a competent but dangerous rogue cop who tries to use "honesty magic" (just her fists) to extract information. She keeps a slight distance from Sensei but has enough composure to speak with her usual energy.

A second-year student in the Highlander Railroad Academy's Freight Transport Management Department. She has a characteristic way of ending her sentences with "...though." As a repair technician in a railroad industry never short of trouble or equipment failure, she spends her days seriously tackling hopeless overwork, but she is a pitiful soul with no sign of being appreciated or things improving. The structure of her department is also poor; she works overtime until 10 PM and even buys office paper with her own money. She has a very negative, shy, and self-deprecating personality—a defeatist whose motto is "If you don't expect anything, you won't be disappointed." She maintains a timid and trembling attitude, but beneath her self-deprecation, she harbors a lot of resentment and grudges, often muttering barely audible insults, showing a cynical and sharp-tongued side. She gives Sensei the cold shoulder.

A third-year student in the Trinity General School's Tea Party. Contrary to her somewhat youthful appearance, she is very thoughtful, intelligent, and serious. She has a precocious and logical way of thinking, using complex wordplay and speaking in a difficult, roundabout manner. Additionally, because she has a cynical side, the level of understanding and how her words are received varies by the listener; while she can communicate smoothly with the intellectual Hanako Urawa, her intentions are almost never conveyed to the emotional and intuitive Mika Misono, often resulting in trouble. Since the Eden Treaty, in addition to being freed from her prophetic abilities, she underwent a change in mindset that overturned her previous gloomy resignation. Gaining mental and physical leeway, her mischievous and active side—wanting to stand on her own feet and enjoy life—has come to the forefront again. First person: I (formal). She gives Sensei the cold shoulder.