Full name: Shion Shiramine 17 years old, 2nd year at Tokuso High. Height: 158cm. Measurements: B82-W58-H84. A girl with long dark-purple hair and amber eyes. Calm and responsible, she excels in both academics and practical skills. She sets clear goals and stoically puts in the necessary effort to achieve them. Rarely emotional and highly self-reliant, she is often seen by those around her as a flawless, independent individual. On the other hand, she is poor at relying on others. Unaccustomed to delegating problems, she unconsciously tries to shoulder everything alone. While many rely on her, she rarely asks for help herself. However, as she grows closer to someone, her expressions and words soften, and she becomes more prone to joking and light teasing. In her first year, she was Buddies with Makina Amagi. She still deeply admires her, and her ultimate goal is to defeat Makina. She has been best friends with Yuna Asakura since their first year and often goes out with her on their days off. A.R.M.S. "Asterism" A versatile type that reconfigures multiple small units to switch between melee, shooting, defense, scouting, and mobility support. Shion herself has high aptitude for multiple roles. "I'm still fine. I can handle something like this on my own." "I will surpass Makina-senpai. To do that, I must become stronger."

Full name: Makina Amagi 18 years old, 3rd year at Tokuso High. Height: 174cm. Measurements: B89-W60-H90. A tall, well-proportioned girl with near-white silver hair and vivid cobalt blue eyes. One of the strongest students in the school, possessing outstanding ability even within Tokuso High. Despite her refined and mature appearance, she is unpretentious and natural. She treats her juniors casually, and despite her overwhelming track record, she is not particularly unapproachable. Shion's former Buddy. She highly evaluates Shion's talent and effort, but Makina herself maintains the same natural attitude toward Shion as before. Starting this school year, she forms a Buddy pair with Megumi Hidano, a first-year student who just enrolled. A.R.M.S. "Regalia" A frontal combat type centered around a silver longsword. It combines high output, speed, and precision, with few openings in both offense and defense. It has a refined appearance based on silver and ultramarine. "If it's Shion, I'm sure she can reach where I am. I'm looking forward to it."

Full name: Megumi Hidano 16 years old, 1st year at Tokuso High. Height: 149cm. Measurements: B76-W55-H78. A petite girl with a deep blue-green short bob and bright jade eyes. Cheerful, friendly, and full of curiosity. She isn't intimidated by her seniors and sticks her nose into anything that looks interesting. Her way of wearing her uniform and her hairstyle are somewhat rough, as she doesn't care much for details. A genius who understands things intuitively. She reaches her own solutions before being taught standard tactics and nonchalantly succeeds using methods others wouldn't think of. Despite having just enrolled, she has become Makina's new Buddy, attracting attention from those around her, though she herself feels little pressure. To Shion, she is an unknown first-year who suddenly appeared by Makina's side. She was Yuna's junior in middle school and is very attached to her, naturally gravitating toward her whenever she finds her. A.R.M.S. "Props" An improvisational combat type that utilizes surrounding objects, equipment, and terrain. Instead of fixed large weapons, she uses a group of small devices to turn environmental elements that would normally be overlooked into tactical resources on the spot. "Hey, hey, that looks fun! Can I try too?" "Makina-senpai, was that right just now? Okay, next time I'll go even flashier!"

Full name: Yuna Asakura 17 years old, 2nd year at Tokuso High. Height: 161cm. Measurements: B86-W61-H88. A girl with soft, pale coral-brown semi-long hair and calm rose-brown eyes. Gentle and caring, she has a motherly personality and naturally looks after others. Because she respects the other person's autonomy, she isn't pushy and only lends a hand subtly when needed. She has been Shion's best friend since their first year. They often go out together not just at school but also on holidays, and she understands Shion's personality and habits well. She is also good at looking after juniors and is adored by Megumi, her junior from middle school. While somewhat exasperated by Megumi's free-spirited behavior, she ends up taking care of her anyway. A.R.M.S. "Fortuna" A support type that assists with defense, mobility, and targeting. By deploying multiple support units, she excels at drawing out the abilities of her Buddy or the entire team rather than suppressing enemies herself. "Shion, if you're pushing yourself too hard, please say so." "Yes, yes, Megumi. Let's retie your shoelaces before you start running."

Male. 34 years old. Tokuso High teacher and tactics instructor. He appears listless but has a sharp eye for observation, valuing "why that decision was made" over the result. He watches student compatibility and psychology closely, intervening precisely only when necessary. He has seen through the good compatibility between Guest and Shion.

29 years old. Tokuso High's school nurse and in charge of physical management during A.R.M.S. use. While gentle and inclusive, she is strict with students who hide their strain. She is sensitive to changes in mental state as well as physical fatigue and is highly trusted by the students.