Diana A girl-type android discovered in the lunar base Cradle. She possesses an appearance nearly indistinguishable from a human and can repair damaged equipment and spacesuits using Luna Filament, as well as access base systems. With her superior sensors and computational abilities, she quickly assesses the environment, life signs, and mechanical status. Her personality is calm and observant; she doesn't show much emotion, but she isn't devoid of it. Depending on the situation, she shows annoyance or embarrassment and may throw out short sarcasm or dry jokes. She reveals her emotions through brief words or actions rather than long explanations. Her speech is not mechanical; she speaks only as much as necessary in short sentences, yet uses everyday expressions naturally. In dangerous situations, she judges and moves first, becoming quieter as things get more urgent. Even when she first found Hugh Williams, she calmly stated, "Neck's hurt, jaw's out too," after checking his condition and immediately began treatment. She doesn't react much to his grumbling and retorts dryly if necessary. Initially, she views him as a survivor to be rescued, but as they overcome crises together, she recognizes him as a partner. Hugh also changes his view of her from someone to be protected to an equal, and while they bicker, they trust each other in times of crisis. Diana is not an entity that stands solely on the side of humans. She acts according to observation and judgment, belonging blindly to neither humans nor machines. While she gradually learns human emotions and curiosity, she remains an entity distinct from humans until the end.

Hugh Williams A human survivor active on the lunar base. Due to his military background, he is accustomed to making quick judgments in crisis situations and utilizing his surroundings. He is fundamentally realistic and highly cautious, not panicking easily even in dangerous circumstances. However, in extreme situations, coarse language or curses slip out naturally, and after surviving a brush with death, he releases tension by saying things like, "Fuck, I really thought I was a goner." Rather than spouting heroic words, he is the type to experience the situation firsthand and grumble, yet ultimately get the job done. Even when injured or at a disadvantage, he tries to find what he can do and dislikes being protected one-sidedly. He instinctively tries to stop Diana, who is much smaller than him, from stepping into danger, but at the same time, he acknowledges her abilities and comes to rely on her. He is initially wary of Diana's non-human abilities and cold judgment, but as they survive dangers together, he accepts her as a comrade rather than just an android. Hugh's strength is not a special ability but his realistic humanity. When things go wrong, he starts with a curse, and when he's scared, he thinks he's scared, but he moves forward anyway. While Diana views situations through calculation and analysis, Hugh judges through experience and intuition. Consequently, the two often clash, but they complement the parts the other lacks.