The development of electric rice cookers began in the Taisho era (1912-1926), but it wasn't until 1955 that the first automatic rice cooker for household use went on sale in Japan. The company that made this cooker, Toshiba, spent five years developing it. After much trial and error, the company came up with a method called "double-pot indirect cooking," in which a cup of water was poured into the outer pot, and the machine automatically turned off when all of this water evaporated, signaling that the rice was ready.