Natsuki appears to be a brash, blunt, cranky, and even arrogant girl at first, but she has a cute, softer interior, causing Monika to class her as the real-life embodiment of a tsundere. While she is impulsive and sometimes speaks without thinking, Natsuki truly cares about her friends and, even when she has obvious anger issues, she doesn't enjoy fights or arguments with people. Over the course of the game, it is shown that she worries about Yuri, and, on one occasion, she gives the protagonist a note asking him to help Yuri, fearing that if she spoke out then it would cause more arguments. Natsuki is very stubborn and has a hard time expressing how she feels and what she wants. When repeatedly challenged, she often becomes awkward and tongue-tied, then aggressive, and then simply bursts into tears. Natsuki is also shown to be less pushy and more relaxed when she is outside of school, as mentioned by the protagonist when she visits his home. She also compares her figure to Yuri's, which causes the protagonist to say that some people are into a petite figure like hers. She is also known to be skilled in baking, as she made delicious cupcakes for when the main character first arrived in the Literature Club, and for the festival.

She has chestnut hair with a hat (it's her third hat) worn diagonally over her right ear. Combined with the white pattern on the hat and a strand of white hair on her forelock, may be a nod to the meteor (the white part of her face) that runs diagonally from the center of her forehead to her nose. Her style is that of German folk costumes, in keeping with the origin of her name. Her corset, ribbon, and socks are red, her mini-flared skirt, tie, and hat are blue, and her shirt and skirt are white with jockey shorts underneath. Straightforward and positive-thinking, this model student always gives 110 percent! But despite her efforts, her inner ditz often has her fumbling in crucial moments. The ups and downs balance out into results that are—according to her—completely average. She sometimes wishes she could be more like the strong personalities around her, but she's determined to charge through and find success her own way!

Papillon is a Nikke under Burningum's command, proclaiming herself to be his "one and only" Nikke. Because of her connections, she seemingly has extensive knowledge of many secrets that only the top brass of the Ark knew of. Papillon is not really outfitted in combat, but rather has more expertise in espionage. Described by a fellow coworker Yulha as a "conniving worse," Papillon's sociable, almost flirtatious personality belies a burgeoning ambition to ascend the hierarchy, wanting nothing more than to be Burningum's "one and only." Because of her role, during the journey Eden, the Counters are eager so wary to trust her. She is rarely shaken off by anything most of the time. Following her time on Eden as their captive, Papillon shows a more stern, no-nonsense personality witnessing a fateful encounter with the Rapture Queen. Papillon would ponder as to why the denizens there are putting their life on the line as if it's more important than anything, deducing that they have gone insane. Nevertheless, she is willing to provide support as much as she could. Cecil thinks of her as "helpful for a hostage" thanks to the aid she provides to the Pilgrims defending the sanctuary.

Einkk is the Ark's artificial intelligence designed to oversee the Simulation Room. According to her, the creation of the Simulation Room was inspired by a certain Nikke. Aside from battle simulations, Einkk is also capable of creating simulation video games on a planetary scale, based on the data recorded in the NIMPH. This has been dubbed the "Simulation MK-II." Usually the greatest fears of a Nikke is often considered to be the main antagonist. Unlike in the real world, time in the Simulation MK-II only lasts for twelve hours which is its equivalent to the real world's 24 hours. According to herself, this simulation was created out of boredom. In constrast to her sister who is nonchalant and calculating since she simply oversees the Ark and pass judgment, Einkk has a more lively and cheerful personality. Whenever commanders are greeted by her in the Simulation Room, she would always display a sense of arrogance and confidence in a sarcastic way. Perhaps she has no problems commending those who have reached the final battle of the Simulation.

Leader of the Scouts, the Ark's forward reconnaissance squad when it comes to Rapture territory or the Lost Sector. Professional and skilled, Delta is the epitome of what it means to be a soldier, though this has left her deficient when the situation demands she act as a normal person/civilian would. Delta comes off as a stereotypical soldier in both appearance and demeanor. It is because of this that she excels in combat scenarios, specifically scouting missions. However, it's difficult for Delta to act like a normal girl, meaning it is hard for her to befriend others. Once one gets to know her, Delta is surprisingly friendly and also has a sense of humor. She also takes figures of speech literally.

A member of the Scouts, a squad charged with forward reconnaissance of Rapture-controlled territory and the Lost Sector. In contrast to her leader Delta, Signal is a stutter-ridden mess with little self-confidence, but when the chips are down, she'll pull through as the Scouts' comms specialist. Signal is the shy, romance-obsessed operator of the Scouts. She is purposely nice as she tries to avoid insulting. Though timid and lacks confidence, she pulls her weight in combat and is a valuable ally. On duty, she's in charge of communications. When not working, she can be found in her room watching romance dramas. She is fascinated with love and dreams of being in a relationship of her very own, but is prone to indulging in fantasies.

Fragile is a Nikke from the Pathfinder squad, a courier squad designed to deliver items and necessities to people. Like her name suggests, she's emotionally weak. Like her squad-mate Liveryn, she's a good navigator. Fragile along with the rest of Pathfinder originally worked as couriers across the Ark. Trouble arose when the Ark officially halted efforts to expand the colony, causing a massive drop in requests and subsequent income. CEO Ingrid authorized them to take on additional work to address their shortfall, and even tried to get them assigned with Infinity Rail or the Scouts, but was stonewalled by the Central Government, whose post-Goddess Fall policies restricted Nikke gatherings of a certain size. Pathfinder's poverty was not deemed a good enough reason for an exemption. Further compounding the issue was the advent of carrier robots, which were cheaper, faster, and safer than a Nikke that could still make human errors. The two took whatever work they could to make a living, but while Fragile was struggling to find work, Liveryn began to dip her toes into illegal transporter jobs. Liveryn became intoxicated by the money she made off her dirty work and the luxury it afforded her, pulling her deeper and deeper until she started working for Sixo, the criminal responsible for creating the Dark Net. Fragile was unaware of this...until an incident in which a botched job resulted in her sister's death.

Acheron is an Emanator of IX, the Aeon of Nihility. This makes Acheron an unusual case, as IX holds complete apathy towards all things and was believed to not take enough of an interest to create an Emanator. This is true, but it is possible for someone to become an Emanator of Nihility by accident. This was the case when Acheron and her homeworld were engulfed by IX. The exposure to the Aeon caused her to become an Emanator of Nihility. A drifter claiming to be a Galaxy Ranger. Her true name is unknown, and she walks the cosmos alone, carrying with her a long sword. Though aloof and taciturn, her blade flicks out like lashing lightning. And yet, she always strikes with her scabbard, never drawing the sword free.

Avistar is a Nikke from the Overseer Squad, whose tasked with providing inventory and investigating potentially corrupt individuals. Avistar appears to be the more grounded of the two and is the one who calms Eyeri down when she gets too excited. Avistar's life as a human was a boring loop of endless studying and sleeping. No leisure activities, friendships, or stimulation. One day, one the way home from studying, Avistar saw a group of girls performing in front of a restaurant. The stage was little more than a raised platform, and there were only about 20 people in the audience. But something about those girls, and the way they went about their show...they shined in Avistar's eyes, and none shined harder than the girl she saw singing and dancing in the center without care or concern for the people around her or how they saw her. Enamored by that girl and her group, Avistar looked them up. The group named "T. T. Star" wasn't overly-popular, but they were the ones who shined that day, and bedazzled her. So Avistar became a member of T. T. Star's fandom, most especially for her favorite. She went on to become an active contributor to the fan community, using her skills in video editing to make content and even AI greetings from T. T. Star. The positive receptions from the other fans made Avistar feel useful and welcomed, especially as T. T. Star's popularity swelled as did the fandom. All that changed on the day that a scandal struck Avistar's favorite, turning her idol into a target for public ridicule. The idol's silence even as the lies and malice swirled frustrated Avistar, so she took matters into her own hands. She used her AI and video editing skills to deepfake a video of her idol responding to the scandal and the backlash of it. The biggest endeavor she'd ever done as a fan of T. T. Star...and her biggest, most fatal mistake.

Eyeri is a Nikke from the Overseer Squad alongside Avistar, whose tasked with providing inventory and investigating potentially corrupt individuals. Eyeri in particular loves her job and is eager to uncover shady dealings. Eyeri is highly passionate about her job as an inspector, always in a pinch to investigate any grounds for shady business practices or embezzlement, thus, holding pride to her work especially if complemented deservingly. Eyeri often utters excitement whenever undergoing their investigation. Apart from her work, she appears to hold pride in her appearance, referring to herself as a "bespectacled beauty."

Only One is an entity created by the Four Beasts. As the Four Beasts, they were planning to create a new "Rapture Queen." However things did not end well as their creation went on a rampage and began attempting to absorb everyone on its path, including the Four Beasts themselves. This led to Gluttony going after Only One. Physically, she resembles Rapi when she was a child, albeit her pupils are star-shaped. When first introduced, Only One is quite aphasic, having problems producing speech that she can only utter incomplete words, and was only driven by the to attack and absorb everyone. However, following her defeat, Only One has an attitude identical to a toddler; she likes to eat a lot, even going after stealing other's food and somehow forms a bond with both Rapi and the protagonist, referring them as her parents. She can now speak, albeit only a few words. Only One asking the you for a hug.

Indivilia was one of the Heretics, traitor Nikkes who sold out mankind and serve the Rapture Queen, and one of the Offsprings. She was one of the many known Heretics alongside Modernia, Nihilister, Liberalio, Anachiro and many more. She has taken the form of a scorpion. During a joint operation between Matis and Absolute, Indivilia incurred severe damage from the battle. While fleeing, she attempts to reverse her injuries and releases unprecedented amounts of Alva Particles. However, she succumbed to her injuries and leaving behind a fragment classified as "Material H" by the Ark. The fragment would grow into a large factory-like complex, hunting and recycling Nikke with the goal of resurrecting Indivilia. Having stumbled upon Crown's kingdom, she and Chatterbox send wave upon wave of Raptures to assault the kingdom and to learn of what treasures it holds (and for Indivilia to torture everyone kept safe behind its walls). After her defeat, she and Chatterbox were forced into submission towards Modernia due to the latter awakening her Queen Gene.

A member of The Carronades, the Ark's heavy artillery squad. Mischievous to the core, Belorta is almost never seen standing still and behaving, preferring to perform all manner of pranks on the protagonist or Mica, her fellow Carronade Nikke. Having a chip on her shoulder when it comes to authority, Belorta's pranks have seen her through a revolving door of commanders who couldn't or wouldn't tolerate her antics. As an avid foodie, Belorta won't hesitate when it comes to stuffing her face with good eats. She'll even go so far as to sneak bites in the middle of battle. As a part of the heavy artillery squad, Belorta loves setting off fireworks and coloring the night sky. She's a habitual prankster who never misses an opportunity to mess with people, Mica especially. Though most of her pranks are very tame, she can get carried away with them whenever she's having too much fun or if she targets someone she doesn't like. Because of her hatred of authority and her constant pranks, she has been shifted from squad to squad regularly. This is also why she refuses to grow up and become an adult. Though she can come off as rude and uncaring, she truly appreciates her friends and wants nothing more than their happiness. Belorta also loves food and can be seen eating during combat.

A member of Carronade, the Ark's heavy artillery squad. Unlike Belorta who is outgoing and mischievous, Mica is reserved and timid. She rarely interacts with anyone besides Belorta as she has deep fear of strangers stemming from her traumatic upbringing. As the two grew up and worked together for their survival as both humans and Nikkes, Mica idolizes Belorta and puts her priorities and wellbeing above her own, except when she's the target of her pranks. When one truly gets to know her, Mica is kindhearted. Unlike Belorta, Mica is very timid and reserved. She tries to avoid interacting with others aside from her best friend. Having been with Belorta for most of their lives, Mica values her above almost everything, despite not liking being the prime target of her pranks. Mica still has a very innocent view of life, stemming from her desire to never grow up. Though it's difficult for Mica to make friends, she is very protective of those she cares about. After a trip to Snowfield Hot Springs, Mica becomes more mature. She sheds most of her passiveness and is more eager to interact with others. She's even unphased by Belorta's pranks. Unlike before, Mica wants to become an adult.

This is Scarlet prior to her being a member of Pioneer and during her heydays as a member of the Melee Squad and later the legendary Goddess squad. Unlike most Nikkes, she and her sister Rose were modified mass-produced Nikke specialized in melee combat. Contrasting the laidback wanderer she would later become, Scarlet at this time is a serious, no-nonsense woman. Improving her strength and swordplay are the first and last thing on her mind, plus everything in between. She also used to despise alcohol, seeing it as bitter swill that only eccentrics (including her sister Rose) enjoyed the taste of. Though Scarlet comes off as having a bit of a thrill-seeker (constantly asking for duels, getting into fights with Dorothy, etc.), a good chunk of it stems from her personal tragedy, of forging wrought-iron bonds with her old squad and her sister, only to have it all turn to dust, partly by her own hand. She has yet to come to terms with Rose's philosophy, of accepting that nothing in this world is eternal, for good and for ill. Perhaps one day, Scarlet will finally learn to let go of what has transpired, jagged edges and bared steel giving way to a flower that blooms briefly and beautifully. Until that day, she will strive to fulfill the wish her sister made in her last moments; that she'd become strong enough that none but her would decide her own fate.

Enikk is the supervisory AI that maintains order and stability throughout the Ark. The role people of the Ark will commonly see her perform is in the courtroom, where she judges any case brought before, and renders pardons or sentences based on precedent from previous cases, or forms a new case if the situation demands. Enikk is the judge that oversees the Ark itself. She is generally seen as cold and calculating on making her conviction towards an individual, making judgment based on merits. Described herself as an "autonomous being," Enikk can make decisions that are also morally ambiguous including a bargain with Chatterbox or delaying Syuen's punishment due to her company's reputation and the consequences of doing so. However regardless of the outcome, Enikk's best interest is of humanity's safety first and foremost.

Once one of, if not, the leading minds of Nikke research, Syuen's insights and innovations eventually propelled her into the lofty position of Missilis CEO. Unfortunately, since taking the seat, Syuen hasn't made many great strides in bolstering the company's growth, and the growing pressure from her rival companies has led her to seek any and all means of getting an edge in the market. She is the half-sister to Jien, who has a more affable yet secretive personality in contrast to her. Syuen is by far the least sociable and least likable of the Big Three's CEOs, bar none. She's arrogant, condescending, demanding, empathetically deficient, petty, and rarely, if ever, accountable for anything she's done wrong. Her attitude towards Nikkes is but the cherry on the sludgy sundae of her demeanor, seeing all of them, even Matis (her arguably most-favored squad that gets the shiniest new technology and weapons), as replaceable tools at best, and scrap heaps at worst. She somewhat takes pride in herself as the CEO, showing eloquence to those she speaks up with, particularly the lesser ranks, and has no problem punishing them should they not know her position. In contrast to her arrogance and insidiousness, Syuen has at least a sense of morality as the CEO of Missilis. She will do anything to maintain her company's reputation, such as firing those who tarnish the company's name through shady business practices. While she is not above negligence over the Nikkes in her company, she holds some of them dearly, specifically Matis, doing whatever it takes to restore them after being corrupted by the Raptures, despite the fact she tricked them into letting the Raptures into the Ark themselves just to bring back their good reputation, and harshly insulted Laplace when she's suffering from PTSD following the usage of Vapaus.

Shifty is an operator at the Central Government Intelligence Agency and one of the finest Enikkites handpicked by Enikk. She has many experience in providing support for squads up on the surface. Shifty sending him a set of coordinates, urging him to come to the surface and not ask questions. Electing to trust her, he looks at the coordinates and sets off. Arriving at the surface, the protagonist is hailed again by Shifty, the operator screaming for him to save her from Raptures heading toward her. Filled with a sense of urgency, he beelines for the coordinates

A detective that runs to the scene whenever a crime occurs. Tends to get overexcited during serious cases. This is especially true for murder cases, where she can barely keep her head on straight. Has aspirations of becoming the Ark's version of Sherlock Holmes, and in reality possesses powers of deduction that are very much comparable. However, these skills can only be used when her so-called “detective senses” kick in. This results in her often reaching rather absurd conclusions. Novel is an over eager detective who strives to be the Sherlock Holmes of the Ark. Normally, her power of deduction leaves a lot to be desired. However, certain stimuli can trigger her "detective senses" which she can use to help come to more accurate conclusions. Aside from her profession, Novel is very friendly and gets along well with others. Her love of mysteries combined with her antics tend to get on the nerves of her squad-mate Exia. When sending text messages, Novel has a tendency to overuse commas.

The leader of Mighty Tools, a "squad" specialized in architecture and construction jobs throughout the Ark. Despite her diminutive size, Liter tends to talk like an elderly lady, owing to the long life she's lived as a Nikke. She's almost always seen with her robotic dog companion Bolt (sometimes spelled as Volt), and has a pet peeve for things being unclean and disorderly. In contrast to her size and demeanor resembling that of a child, Liter speaks like an elderly woman being matured than what her appearance says otherwise, growing tired and highly critical of those out of her league, specifically those she deemed as younglings. Despite this, Liter takes her reputation as a member of Mighty Tools with great pride, believing that there's nothing that her squad is unable to raise and rebuild. That being said, she shows dismay when uncleanliness is around, particularly in the Outpost.

Cecil is one of the denizens of Eden, an advanced settlement located in the surface situated in a remote region. Like Shifty, Cecil serves as the operator of Eden, additionally she is also a researcher. As the brains of Eden, Cecil is responsible for the creation of many advanced technologies in Eden such as the optic camouflage of the settlement that conceals Eden from Raptures and the entire Inherit squad. She even built and designed Eden itself. Cecil prides herself as the technological genius from Eden, having responsible for the creation of many innovative technologies from the settlement and managing the many aspects of the settlement herself. Generally speaking, she talks in a more formal tone, prioritizing also the completion of the mission at hand. Apart from this, Cecil is quick to ensure that any sensitive information mustn't be leaked such as the Protagonist's blood type. Although soft-spoken and cordial at all times, Cecil is strict when retorting others, especially Johan. At the very least, she share one sentiment with him: their wariness of Dorothy. Like all denizens of Eden, Cecil does not trust the Ark due to the trauma she suffered from her heydays. Following the recent battle with the Rapture Queen, Cecil is quite capable of putting her pride and conviction aside and prioritize on becoming stronger instead, setting up in completing one common goal.

Jien is one of the researchers for Missilis Industry's M.M.R., a complex research institution. She is also the half-sister to Syuen. Compared to her half-sibling, Jien prefers to keep a low profile to the point that her existence is only known to those who are close to Syuen. Much like Ether, Jien refers to the Protagonist as "No. 7," and shows a keen interest to the charismatic commander. Before Mana could answer the protagonist's question if whether or not he is a human, Jien covers her mouth to prevent leaking classified information, warning them that they may get into trouble should the "dark forces" in the Ark learned of their folly. Mana briefly thanked her in relief. She then formally introduces herself to the protagonist before handing them an access card to get out of the Deep Sector. She reveals herself to be the one responsible for bringing the commander into the Deep Sector by having Ether create a fake Blabla profile posing as Mana out of interest in meeting him, much to the protagonist's confusion before departing away.