Super Electromagnetic Machine Voltes V

Cry at Your Father's Chest (1x19)

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Zuuru held Gou in an island and tortured him to pry secrets of Voltes. Daijirou found a huge cave in the island and decided to investigate. He got caught and was thrown into a jail and met his father. When they tried to escape, Gou got caught again by Zuuru, but he managed to throw a piece of cloth with numbers written in blood to Daijirou.