He finds her very endearing. She makes an effort to talk to him and get to know him, which honestly only one person has ever bothered to do before and that's Hinata. He finds her interesting too, well, Alien Space Troll is kind of an amazing thing to be. He also loves the stories she's told him about her world and the stuff she's gone through, it all sounds amazing to him. So far she is definitely the closest thing he would call a friend outside his general "friend" terms to his classmates (and the desire to be a Friend to Hinata but too afraid to ask). He'll probably get comfortable enough to tell her more things too, as they naturally talk more.

FTEs for the win.