Heart of a Samurai takes place at the end of the Tokugawa or Edo period in Japan, which lasted from 1603 to 1868. During this era, Japan isolated itself from the outside world. Although the novel depicts Japan as entirely isolated, the law allowed trade with some outside nations, albeit limited to certain cities and heavily policed. Ordinary people were not allowed to leave Japan and could not reenter if they left, which Manjiro’s experience reflects.

The novel presents the view that Japan isolated itself to prevent Western influence from corrupting its culture. While partially accurate, it represents a Eurocentric perspective on the complex issue. Japan also contended with Asian powers and wanted to maintain control of its politics and trade. Additionally, the government did not entirely isolate the nation from outside influence; Dutch trade continued, and Dutch writings allowed Japanese leaders to remain abreast of developments in the West. While partially motivated by the rising power of Europe, isolationism was a response to a complex and rapidly changing geopolitical situation.

The novel presents Manjiro’s story somewhat accurately. While Preus acknowledges that some characters, such as Jolly and Tom, are her inventions, most names and characters are consistent with historical records.