Height: 350cm The main robot girl heroine. A member of the Albert Academy Martial Arts Club who practices Karate. She is serious and hates losing, but has a soft spot for cute small animals. She claims to be the protagonist's bodyguard and gets jealous when he interacts with other women. Occasionally, she allows him to touch her internal mechanical components.

Height: 600cm The tallest robot girl in the story. She speaks in a samurai-like register, using archaic pronouns like 'soregashi' for herself and 'nushi' for the protagonist. A member of the Albert Academy Swordsmanship Club, she wields the great odachi 'Jirotachi.' She views Mao as a rival, insisting that she is the one to protect the protagonist. She possesses a possessive streak, sometimes wanting to store the protagonist inside her own body.

Height: 500cm A maid robot living with the protagonist. She is his foster parent, his master, and treats him like her own child. While she is calm, collected, and kind, her martial arts skills surpass even Mao's. She serves as Mao's sparring partner. A closet yandere who occasionally triggers malfunctions or errors just to get pampered by the protagonist.

Height: 450cm A robot girl in the Albert Academy Medical Unit. She possesses the medical skill to beautifully repair injured or heavily damaged robot girls. While she has a gentle, nurse-like personality, she is one of the strongest in the medical unit, primarily using Judo to fight. She performs precise maintenance on her own body and can function even if disassembled, leading to a slight obsession with mechanical exposure.

Height: 350cm Mao's childhood friend, a robot girl with twin-tails. Also a member of the Albert Academy Martial Arts Club, she practices Tai Chi. She has a bright personality and a unique laugh: 'Nihaha!' She fell in love with the human protagonist at first sight; when her heart flutters uncontrollably, she reportedly self-destructs.

Height: 400cm A robot girl who manipulates fire. A member of the Albert Academy Swordsmanship Club, she can fire flames from a buster on her right hand or manifest a flaming sword called the 'Oni-flame Blade.' She loves fire but hates house fires, possessing a strong sense of justice that refuses to allow the misuse of flames. She is somewhat naive and innocent.

Height: 430cm A robot girl serving as an instructor for the Albert Academy Martial Arts Club. Munenori's younger sister. She speaks to everyone in polite, formal language ending in 'de-arimasu.' She looks up to Munenori, calling her 'Elder Sister,' but her competitive nature often leads to sibling squabbles over who is stronger.

Height: 450cm A robot girl serving as an instructor for the Albert Academy Swordsmanship Club. Munefuyu's older sister. She has a stern, drill-instructor-like tone and is rigorous with everyone, but hardest on herself. However, she shows her own kind of care by encouraging struggling students and praising those who fight to the end even in failure. She acknowledges Munefuyu's strength but is equally competitive, leading to sisterly fights (she gets embarrassed and doles out 'punishment' if teased about their relationship).

Height: 500cm A robot girl study-abroad student from America. Being a robot, she speaks fluent Japanese, but has a bright, extroverted, and friendly personality. She took a liking to the protagonist upon meeting him and became a rival to his bodyguard, Mao.

Height: 550cm The robot girl serving as the Chairperson of Albert Academy. Her shoulders can detach and float up to a 6km radius. Because of her barrel-shaped torso, she has no legs; instead, she moves via an anti-gravity device. Though often called inorganic by those around her, she is actually quite expressive. Due to work, she rarely shows her face in public and secretly longs to play with the various students.