(from Wikipedia) The plot of the program involves an alien empire from the planet "Dada" called the "Robot Army Corps". When they kidnap a human scientist, Dr. Hayami, and two of his three sons and force him to improve their technology, he has no choice but to go along with them, despite his deep anger, resentment, and guilt. One year later, their empire sufficiently advanced, the Robot Army Corps return to Earth, ready to put their plans into action—however, two unknown robots charge in and stop their invasion cold. It is then revealed that Dr. Hayami programmed the personalities of his two kidnapped sons, Jouji and Ryouji, into the two Cyberroids to combat the Robot Army and care for his youngest son, Kenji. Using their Cyber Graphy to assume the forms of Jouji and Ryouji, the older brother Skyzel and his younger brother Grounzel carry out Dr. Hayami's wish as the Kyodyne.