Nuko (ヌコ, translated to Cut or Soft in some subtitles) is a mysterious white creature that Chito and Yuuri pick up on during their journey (episode 10). It has an elongated body with four small limbs. Soft can shape-shift to activate mechanisms, bypass electrical locks, or run computer programs, and has a habit of eating bullets and bombs. It communicates via radio signals and is unable to talk if there is no receiver nearby. After reuniting with the rest of its kind, known as Eringi at a nuclear submarine, it departs with them, albeit somewhat reluctant to leave the girls' company.
- Nuko's name is derived from neko (猫), the Japanese word for "cat", so to preserve the pun, Amazon's subtitles for the anime refer to Nuko as "Cut", while Yen Press' translation of the manga calls the creature "Ket".