This volume comprises a selection of the articles delivered at the Ninth Symposium Platonicum of the International Plato Society, held in Tokyo. The articles cover a variety of chief issues raised in Plato's Politeia (Republic), including philology, ethics, political philosophy, psychology, epistemology, metaphysics, education and aesthetics, together with its reception history. The volume reconsiders the recent achievements and provides new perspectives on this most important dialogue.