'"The Secret Royal Martial Arts of Ryukyu"' by Matuso Sakon is one of the few monographies available on Motobu Uduni, the secret karate and kobujutsu of the royal family of the Okinawan kingdom. Henceforth, the author puts a lot of effort in giving an all-encompassing overview of the history, lineage, and techniques ' unarmed and armed ' of this secret style.
Especially, the aspect of armed combat might come as a surprise since most students of karate have certainly learned that in historical Okinawa harshly enforced laws prohibited the use of weapons and led to the development of unarmed combat systems termed karate. Moreover, the author also illustrates in text and picture that Motobu Udundi was strongly influenced by weapon techniques similar to aikiken or iaijutsu as well as by Chinese armed combat techniques and incorporated them into its curriculum. But also the illustrations of grappling as well as joint lock techniques similar to aikido might provide extensive food for thought; especially if one considers karate to be a combat system consisting only of striking and kicking techniques.
In sum, I would highly recommend "The Secret Royal Martial Arts of Ryukyu'" for reading ' not only for karateka, but also practitioners of other martial arts styles like aikido or iaido. Moreover, Matuso Sakon's book is further interesting for researchers of the history of karate. Nonetheless, a certain care concerning the accuracy of given information is definitely recommended as in all works on karate.
In terms of presentation, however, there are two major points for criticism: First, the layout of the book certainly needs some additional editing. It would improve its readability as well as the quality of its look and feel. Second, unfortunately the given pictures are of low quality. This makes discerning some the technical details very difficult if not impossible. Maybe the author decides in future to publish a second edition of his work with improved layout and pictures. This would definitely be a gain.
Nonetheless, given the uniqueness as well as richness of the provided information "The Secret Royal Martial Arts of Ryukyu'" deserves 4 stars.