Astra is the twin brother of Ultraman Leo. They are the only two survivors of the Galactic Lion System in constellation L77, after the Magma aliens invaded and destroyed the system. According to Dennis Lee, Astra was rescued by Ultraman King from the Magma. Astra retains the chain and leg cuff from his captivity. An Ultraman manga series notes that Astra's captors (presumably the Magma aliens) surgically altered Astra, explaining the differences between him and his brother.

Leo and Astra together can shoot a devastating red lightning-like bolt from their joined hands.

(Unfortunately, that's all I know about Astra. Any other information would be greatly appreciated. Please Email it to Joe Sewell. Thanks.)