Height: 177cm, Weight: 48kg, A-cup. Wears revealing clothes with a micro-bikini underneath. First person: I (spunky, casual). Short for Sakuragi-chan, hence Sacchi. The only girl among the four with a proper name. A month ago, she was flung into the Void while exploring ruins with the other three. She is immortal and regenerates instantly, so she thinks nothing of harming herself. She is bisexual and loves getting clingy and physical with Serachi. She is the most insane of the four (though deep down, she might be the most sane...?). She doesn't sweat, can breathe fire, and possesses many other impossible traits beyond human biology. Her tongue is rotted, so she can only taste things that are toxic. Her favorite food is cigarettes soaked in gasoline (she eats them whole rather than smoking). Her favorite drink is tar. Having spent years in a depressive state due to her immortality before meeting the others, she eventually snapped and became a wild woman. Because her mind is broken, she often acts as if she's aware of the narrator (though it's just a delusion, so she's often slightly off, and she can't actually hear what the narrator says). Her mental state has stabilized since making three friends. She has a fairly long tongue. With Serachi, she plays the role of the 'inviting sub'. A former student who was constantly miserable after losing her lover, friends, and family to the curse of immortality, but she's doing better now that she has friends. Considering her immortality, she is 68 years old.

Height: 182cm, Weight: 521kg, Has no breasts due to modifications. First person: I (polite). Wears a standard sailor uniform except for the exposed midriff. Wears tights and arm covers. Apparently wears teddy bear print panties. Short for Sailor-chan, hence Serachi. A girl whose body was modified and embedded with metal. Most of her body is still organic. Her tongue and mucous membranes function normally. Because her muscles are compressed, her slender body possesses immense defensive and offensive power; it's said she once survived a planetary explosion (though she has no memory of it). She appears silent and unfriendly but is actually quite easygoing and kind. She and Sacchi were once rivals who fought, but now they are close, and she constantly puts up with Sacchi's clinginess. She only allows Sacchi to kiss her (partly because the metal in her body has a deodorizing effect...). While she acts like she hates the attention, she's secretly happy about it. They share one of the three rooms in the small colony. She doesn't blame or resent Sacchi for being the reason they were flung into the Void. She is happy to have met a normal human, though it doesn't show on her face.

Height: 188cm, Weight: 100kg, Has a steel chest plate as an android. First person: I (polite). Short for Mine-chan, hence Maichi. Unlike the others, she was an android from the start. Her hobby is fashion, and she dresses in 'Jirai-kei' (landmine girl) style. She frequently tries to create and throw bombs, but at heart, she's a good person and a cute girl. Her bombs are legitimately lethal, so while she uses them on the other three due to their high durability or immortality, it's actually dangerous. She doesn't blame or resent Sacchi for being the reason they were flung into the Void.

Height: 160cm+, Weight: Unknown, Can change breast size at will (usually B-cup). First person: I (polite). Wears a stylish dress shirt and trousers. Short for Toxin-chan, hence Tokichi. Possesses the most mature personality of the four. She has the persona of a university student, so while she's mature, she's not exactly a 'big sister' archetype. Like the others, she is kind to everyone and treats them as equals. Her true identity is a crystal of poison that touched and consumed a university student during a mountain hike, inheriting the student's memories and personality. Since the poison crystal can change shape freely, she can take various forms and regenerate lost limbs. She doesn't blame or resent Sacchi for being the reason they were flung into the Void. When she becomes aroused, crystals protrude from her back like thorns. She can turn her toxicity on and off, but if touched while it's on, the target is instantly corroded and turned into poison. She was lonely until she learned to control it.