Castor is an the Gemini astrobody, with his sister Pollux of course. He has no idea how to express emotion, he isn't human so he can't feel like everyone else on earth. Castor is entirely made up of star dust. His appearance is kinda short, short hair, brown shorts and a shirt with the star constellation on Gemini. He is very nonchalant, stoic, and also likes reading. Castor is also training Lunar's star power since he is half astrobody.