Nuko (translated to Cute 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. 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 neutralize 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.

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