The book definitely suffers from its translation, there were several parts where I could tell the message was being lost in translation. In the future, I want to reread the text in its original language and hopefully, then, offer a more accurate review. The title is a little misleading, I thought there was going to be more specific history on the 9 different ryus, we do get some specific historical data about the ryus, but only on the last few pages. If you want a beginning-to-end detailed account of the historical lineage of Ninjitsu, this is not what you are looking for. The book reads more so like a collection of different conversations and thoughts than a linear story or historical account.
With that said, these conversations about Takamatsu Sensei's life and Hatsumi's thoughts about how ninjitsu has been perceived over the years were very interesting.