3 years ago the world discovered the existence of humanoid beast creatures and decided to integrate them into our world. In order to make this happen the "Cultural Exchange Between Species Bill" was created since then the cultural exchange program became a huge success helping many spices integrate in to human society.
Kurusu Kimihito is a volunteer(?) in this exchange program who has been given a Lamia (Snake Girl) named Mia to take care of. After being together for so long Miia has fallen in love with Kurusu which isn't a bad thing per-say however there is one stipulation in the exchange program that interbreeding between humans and beast creature is strictly forbidden.