Invented in 1937 by the Japanese army – a wooden box with two electrodes – the modern versions work on the principle of absorption but with equal quantities of rice and water. They are hailed by the majority of the world’s population as indispensible, and so simple that many don’t come with instructions. The benefits are that they cook the rice well, with minimum effort, and keep it warm. In households where rice is eaten daily and warm portions need to be ever ready, one can understand their importance.