Colin Ford as Kazuto Tokino (UFO Princess)

Kazuto Tokino is the proprietor of the Tokino Bathhouse, which was formally run by his grandfather. Even though he's still in high school he decided to run it in order to honor his grandfather's memory. The alien princess Valkyrie crashes her spaceship into him and kills him only to bring him back by giving up part of her soul, he is left in love with her but in her current condition as a young child it seems as if they are not meant to be together. Kazuto does whatever he can to protect her and keep his business running through all the chaos she causes. 

Colin Ford made a lot of his career playing children who were very mature for their age, and now that he's 20 i think he would be really good at playing someone like Kazuto who is 18 and very mature and responsible for someone his age. Colin is also not a stranger to sci-fi fantasy films and tv (doing both Supernatural and Under The Dome) and would be a great choice try out UFO Princess Valkyrie.