As a child, Natsuki doesn't fit into her family. Her parents favor her sister, and her best friend is a plush toy hedgehog named Piyyut who has explained to her that he has come from the planet Popinpobopia on a special quest to help her save the Earth. Each summer, Natsuki counts down the days until her family drives into the mountains of Nagano to visit her grandparents in their wooden house in the forest. One summer, her cousin Yuu confides to Natsuki that he is an extraterrestrial, and Natsuki starts to wonder if she might be an alien too. Later, as a married woman, Natsuki feels forced to fit in to a society she deems a "baby factory" but wonders if there is more to the world than the mundane reality everyone else seems to accept. The answers are out there, and Natsuki has the power to find them. Dreamlike, sometimes shocking, and always strange and wonderful, Earthlings asks what it means to be happy in a stifling world, and cements Sayaka Murata's status as a master chronicler of the outsider experience and our own uncanny universe.