Fumiko Kaneko was born in the Kotobuki district of Yokohama during the Meiji period in Japan. Her parents were Fumikazu Saeki, a man from a samurai family, and Kikuno Kaneko, the daughter of a peasant, and because they were not officially married, Fumiko could not be registered as a Saeki. She remained unregistered until she was 8 years old, at which point she was registered as her mother's sister, a fairly common practice for children born out of wedlock. Kaneko recalls that the first few years of her life were fairly happy, as her father was employed as a detective at a police office and cared for his family, though they were fairly poor. However, Fumikazu left his job at the police station, and the family moved around a considerable amount over the next few years. Fumikazu was also increasingly drawn to gambling and drinking, began to abuse Kikuno, and became involved with other women, including Kikuno's sister Takano. Eventually, Fumikazu left Kikuno and married Takano.