Hagakure: Trade Like A Samurai (사무라이처럼 거래를 하다) The Hagakure: The Book of The Samurai records Yamamoto Tsunetomo’s views on bushido and the warrior code of the samurai. It was written in the early 18th century and explains many principles of the Samurai warrior. Many of these same principles can be used in business, sports, trading, and investing to achieve a warrior mindset and overcome your ego..