The Hinata household is your typical, everyday Japanese household, it consists of: Aki, the mother who is a manga editor, Natsumi, the older sister that is perfect at school, but bossy at home, Fuyuki, the little brother that is in the occult club at school, and Sgt. Keroro, the frog-like alien that was sent here as part of an invasion force to take over Pokopen (Earth). As the Sgt.'s comrades appear, the only defense against the invasion of Earth are the Hinata household and other friends.