Earthlings chronicles the life of Natsuki, a woman with a deep-seated belief that she is not of this world. Growing up estranged from her own family, she finds solace in her plush toy hedgehog, Piyyut, and her cousin Yuu, who fuel her conviction of being an alien. This belief becomes her escape from the pressures of a society that demands conformity and sees her as just another cog in the 'baby factory.' As Natsuki navigates adulthood with her asexual husband, the shadows of a troubling childhood linger, compelling her to seek refuge in the mountains of Nagano. Here, she searches for the cosmic answers that she believes only she can uncover, all while questioning what it truly means to be happy in a world that feels alien.