Nonagenarian Japanese artist is simultaneously one of the most famous and most mysterious artists on the planet. A wild child of the 1950s and 1960s, she emerged out of the international Fluxus movement to launch naked happenings in New York and went on to become a doyenne of that city's counter-cultural scene. In the early 1970s, she returned to Japan and by 1977 had checked herself in to a psychiatric hospital which has remained her home to this day. But, though she was removed from the world, she was definitely not in retirement. Her love and belief in the polka dot has given birth to some of the most surprising and inspiring installations and paintings of the last four decades - and made her exhibitions the most visited of any single living artist.