The drama centers on the life of its heroine, Oshin. Born in 1901 in a remote mountain village to a poor family of tenant farmers, Oshin is sent by her father at the tender age of seven to work as a servant girl for another family. At the age of 18 Oshin returns to her own family, only to discover that her father wants her to work as a bar maid. Asserting her independence, Oshin instead sets out alone for Tokyo to begin a life of her own.
The story continues through the years up to the present (1983), and follows Oshin's life and struggles: her marriage, her daughter's death, her husband's deep commitment to Japan's war effort and his suicide at the end of the war, and her eventual success as the founder and owner of a supermarket chain.
Played as it is against the backdrop of the events of the 20th century and with the many characters who enter and leave Oshin's life, the drama is more than just a story of one Japanese woman: it is a story of Japan itself.