The story is about a group of aliens with a human-like appearance, which "DearS" (dear friends) are called. Their spacecraft is stranded on Earth, so they are forced to live with the earthlings.
The anime's opening theme is "Love Slave" by Under17 and the ending theme is "Happy Cosmos" by Poppins. The DearS are in fact a grown slave and behave as such: obedient and loyal. Because they are very intelligent they bring this fact to the outside because of the aversion of people towards slavery. Instead, they present themselves as an exchange student, hoping to be accepted in society. A DearS binds to a specific person, which then their "master" is. Because DearS happy of serving their master, they try to find someone to serve.