The evil organization Black Nova was attempting to conquer the world. Their first plan was to mass-produce cyborgs. Innocent people across Japan were kidnapped and abducted. Most couldn't survive the modification surgeries, dying in darkness. Amid this, Mayuko Masaki infiltrated Black Nova to rescue her father. However, her body proved highly compatible for cybernetic enhancement, and she was reborn as Radio Lady Beagle. Yet her heart remained filled with justice. The scientists, seeking to alter her mind, subjected her to horrific torture. Through this process, she was forced to confront the very meaning of her existence.