It is an excellent book in Japanese on Ichimoku Cloud. It covers the three great theories of Ichimoku Kinko Hyo, namely the time theory, the wave theory, and the price projection theory. A great number of charts and examples are used to clearly explain the concepts. You should read it if you want to have a hardcore understanding of the Ichimoku concepts. Absolutely a must-have for every Ichimoku Cloud Trader.
The book author is a very popular technical analyst in Nikkei Financial Daily, also won a top trader for eight consecutive years.