Definition: Also known as the nonhuman girlfriend. They are women who have some sort of ability or trait that makes them more than human and are infatuated with the male lead.
What You Need To Know: Supernatural Girlfriends are from another world. They usually meet their male counterparts by total accident. They will then find themselves living with said male counterpart, much to his chagrin.
The two most common types of Supernatural Girlfriend are aliens and robots. Alien Girlfriends will most likely have crash landed on Earth. They may or may not have a way back home, but choose to stay due to their love for the protagonist. They are more energetic and romantically aggressive than Robot Girlfriends.
Robot Girlfriends tend to be less self-reliant than Alien Girlfriends. The protagonist will most likely have found them deactivated, with little to no memory of their original purpose. Then they turn out to be some sort of super weapon or advanced model. Most Robot story arcs involve them adapting to human life and trying to understand the concept of love.
The Supernatural Girlfriend is the catalyst for a lot of anime shows plots. They drive the story by presenting new and strange challenges for the protagonists. A common gag usually involves the Supernatural Girlfriend going to school with the protagonist, immediately gaining the protagonist resentment and jealously from his fellow girlfriend-less classmates.
But by the end, they overcome these challenges and get together.
Western Equivalent: The concept of the Supernatural Girlfriend isn’t foreign to the west. Show’s like I Dream of Jennie and Bewitched both revolved around magical women with mortal men. The Sarah Conner Chronicles has a young John Connor fall for a female terminator. The movie Stardust was basically a Supernatural Girlfriend movie as well.
Special Note: Supernatural Boyfriends