Shinryaku! Ika Musume-1
She comes from the ocean depths to invade the world of the surface! Humans have abused the ocean for years, throwing their garbage into the seas and polluting it with their industry. In order to strike back, the ocean has begun to send its agents to invade the land! Once all of mankind has been subdued, then the ocean can once more be clean again! The first of such invaders, as far as she knows, is a young squid, though she knows very little of the surface world and may have bitten off far more than she can chew.