Wow... This turned into such a long discussion XD Dragon Physiology and Integration into Human Society 101, anyone?
Seriously though, it breaks my heart a bit to have to imagine what awaits Kanna and Saikawa (as well as Tohru and Kobayashi) down the road... This depressing undertone of a comedy series hurts more than an actually depressing anime. T^T I hope both pairs just treasure all the time they have together.