Whilst not entirely focussed on the economy of post-war Japan, I recommend picking up a copy of Kenneth Henshall's A History of Japan: From Stone Age to Superpower and Andrew Gordon's A Modern History of Japan: From Tokugawa Times to the Present. These two books obviously cover a larger breadth of time than you might want to focus on, but it is helpful to understand just how miraculous Japan's postwar economic recovery was given the situation during the Second World War. Christopher Goto-Jones' Modern Japan: A Very Short Introduction also goes in-depth into the origins, course, and consequences of the economic recovery after the war. All of these books are very much accessible for a layperson, as they explain both the larger context in which the economic policies, changes, and events occurred whilst also (helpfully) linking each economic action to the larger effect (so you do not need a firm grasp of economic concepts to read them). Happy reading!