Originally imported from China through Okinawa, sweet potato is called “Kara-imo” or “potato from China” here in Kagoshima, but in the rest of Japan is called “Satsuma-imo” which literally means “potato from Satsuma,” the old name for Kagoshima. It spread out of Satsuma to the rest of the country in the 18th century.
It was a perfect product for Satsuma where fertile land was quite limited due to volcanic activities. Much of the soil was covered by volcanic ash, therefore could not hold water. Since sweet potato does not require much water as other crops, it became one of the main and most important crops in Kagoshima.
Because of its resilience, sweet potato was most valued in time of disaster and crisis like famine or war. It is believed that when Japan was struck with such disasters, sweet potato saved lots of people from starvation.