Shinryaku! Ika Musume

A young sea creature, Ika Musume, is disturbed by the increasing pollution of the ocean. Determined to retaliate against humans for their actions, she decides to take matters into her own hands and launch an invasion. However, her knowledge of the surface world is limited, and her attempt to take over begins with her trying to break into a beach house. Instead of achieving her goal, she ends up being captured by the house's occupants after damaging part of its wall.