Nuko (translated to Cut in some subtitles) is a mysterious white creature that Chito and Yuuri pick up on their journey. It has an elongated body with four small limbs. Nuko can shape-shift to activate mechanisms, bypass electrical locks, or run computer programmes, and has a habit of eating bullets. It communicates via radio signals and is unable to talk if there is no receiver nearby. It is later revealed to be part of a possibly artificial species that was made to neutralise unstable energy sources such as weapons by consuming them. After reuniting with the rest of its kind at a nuclear submarine, it departs with them, albeit somewhat reluctant to leave the girls' company.