Angered by the pollution in the seas, a squid girl named Ika Musume comes from the sea and declares the invasion of Earth at a nearby yakisoba stand, but isn’t taken seriously due to her small stature. When she goes to plead her case, she is mistaken for a waitress, which puts the responsibility of invading the world into perspective. When she breaks a hole in the store with her tentacles trying to hit a mosquito, the store manager, Eiko Aizawa, puts her to work in order to pay for the damages. Later, Ika meets Eiko’s little brother, Takeru, who goes to great lengths to pretend to be a squid-person so he can be Ika’s comrade. During a rainy day where there are few customers, Ika takes the opportunity to try and take over the stand, but is overpowered by the eldest sister, Chizuru. As punishment, Ika is forced to use her own ink to make Squid Ink Spaghetti, which becomes popular.