Asobi ni Ikuyo!

The story revolves around Kakazu Kio, an ordinary high school freshman living in Okinawa. A girl with cat ears appears before him during a memorial service for one of his family ancestors. The girl calls herself Elis and claims she is an alien. Before long, fanatical alien worshipers and a mysterious government agency are in hot pursuit of Elis, but Kio's childhood friend Manami — who wants to follow in her father's footsteps in the CIA — captures Elis. Kio finds himself having to protect Elis from everyone.

(Source: Wikipedia)