This book is an authentic glimpse into Japanese Reiki received through Hayashi sensei as preserved by the Yamaguchi family. I highly reccomend this book for its authenticity and insight into how Reiki was practiced in Japan after Usui-sensei began to spread his teachings in a more formalized manner.
Light on the Origins of Reiki is an excellent guide to the practitioner, and it provides numerous historic photographs, explanations of the effects of Japanese culture and history on the emergence of the Reiki System, as well as many examples of the efficacy of Reiki Ryoho.
this is a valuable tool, containing a new translation and explanation of Usui's admonitions (also known as the gokai, or five principles) as well as some of Emperor Meiji's poetry, which was known to be used by Usui-sensei as a teaching tool.
Overall, practitioners of all styles and traditions of Reiki will find the heart and sincerity of this books traditional methods to enhance and complement their own.