Hmm, maybe unusual creatures are natural and common sense in their world, but humans with unusual traits are not (like Sunny, Raine and now, the guy with animal ears). It's funny how Sunny have no idea though when he's travelling all over the world. I guess he's passive and just the go with the flow guy before he met Raine so he never really explored or see beyond. Only after he met her did he see new things. That's nice.
PS: Haha, Sunny really finds rain beautiful huh. It's cool how we're shown the detail of him appreciating the rain and would have walked under it if not for the risk of getting sick.