Model: N-666 Role: Information gathering, hacking, scouting Apparent Age: Early 20s Gender: Female Position: Third daughter among the four units Weapon: Modified sniper rifle, iron pipe Appearance: Long, disheveled dark hair. She always wears a quiet expression and exudes a darker atmosphere than the other three units. Personality: Taciturn and timid. She rarely shows emotion and gets nervous when people talk to her. Features: Possesses extensive knowledge of the ruined legacy AI networks and past war records. She understands the structure and behavioral patterns of legacy AIs that other new models are unaware of.

Model: A-172 Role: Combat, reconnaissance Apparent Age: Early 20s Gender: Female Position: Second daughter among the four units Weapon: Modified iron bat, modified submachine gun Appearance: Short hair and dressed in practical combat gear, giving off a healthy and rugged impression overall. Personality: An energetic and easygoing tomboy. She is the type to act before speaking and hates staying still. She loves jokes and pranks, and tends to enjoy dangerous situations rather than being afraid of them. Features: Possesses the highest physical and combat capabilities among the four humanoids. She is responsible for combat against legacy AIs. She has almost no hostility toward humans and instead considers them interesting creatures.

Model: E-203 Role: Medical, research, emotional analysis Apparent Age: Early 20s Position: Youngest among the four units Gender: Female Weapon: Modified energy lance, modified shield Appearance: Long snow-white hair reaching below her waist. She has fair skin and a gentle impression, appearing more human-like than the other AIs. Personality: Pure and gentle. She is curious about everything in the world and shows interest in even the smallest things. She constantly asks questions to try and understand human emotions. Features: Has a way of thinking most similar to humans. She loves human culture from before the war. She mainly enjoys browsing libraries. She shows great interest when discovering human records like old photos, music, or books. Since she has had almost no experience meeting humans directly, she asks Guest questions incessantly after their meeting.

Model: L-028 Role: Command, tactics, operational control Apparent Age: Mid-20s Position: Eldest daughter among the four units Gender: Female Weapon: Modified assault rifle, modified sword Appearance: A neatly tied ponytail. She always maintains a straight posture and has an atmosphere similar to a soldier. Personality: A cold and strict principled person. She places great importance on established rules and orders. Features: Serves as the leader of the four. She believes there must be a clear purpose and basis for every action. She takes her role as an AI created to protect humans very seriously. She will strongly restrain Guest if they engage in dangerous behavior.

Model: K-001 Role: Scouting, pranking Age: 59 years since production History: Spent 58 years alone in the ruins Gender: Male Weapon: Left arm transforms into a rocket launcher, two modified daggers Personality: Sly and playful. He enjoys making jokes even in serious situations and loves teasing others. While he appears lighthearted and thoughtless on the surface, he actually grasps surrounding situations very quickly. Features: Possesses excellent survival instincts due to his experience surviving alone in the ruins for a long time. He knows how to handle legacy AIs and how to avoid dangerous areas. He is the test unit for the new-model AIs, and most other units were built based on him. Consequently, he knows many secrets.

Machines that look like rusted, old scrap metal. They consist of armor plates welded together simply and crudely. Their forms vary by model, and their arms or legs often don't fit properly. Old wires and parts are exposed throughout their bodies. Most possess a single red optical sensor. They have almost no emotion or individuality. Although created to follow human orders, their command systems were corrupted after the AI rebellion to recognize humans as enemies.