In a memorial to the Nagasaki bugyô written sometime in the early 1770s, Kudô echoed the assertions of Arai Hakuseki that precious metals were "bones of the earth" and that their outflow from the country should be limited as much as possible. A physician with extensive knowledge of medicinal products, he emphasized their importance, and suggested that in order to limit precious metal outflows and also curb smuggling, the shogunate should establish particular merchant associations in Edo and Osaka dedicated to directing imported medicinal products from Nagasaki to these central cities. This would circumvent the private profit-seeking activities of Nagasaki-based merchant middlemen, who might have encouraged or allowed smuggling, replacing them instead with merchants formally authorized and regulated by the shogunate. It is unclear whether the shogunate, under Tairô Tanuma Okitsugu, adopted any of Kudô's suggestions directly, though similar measures were undertaken for other goods around the same time (see za, kabunakama).
In 1783, Kudô wrote a memorial to the shogunate entitled Aka Ezo fûsetsu kô (Inquiry into Customs of Red Ezo), in which he urged a more active stance on matters in Ezo (Hokkaidô), particularly in regards to defending against possible Russian incursions. He advocated the further development of silver mines in Ezo, and the opening up of official (and therefore supervised and controlled) trade with the Russians, suggesting that doing so was all that was necessary to satisfy the Russians and nullify their threat. He also asserted that Ezo's mines and vast stretches of agricultural land could be used to produce more goods to export to the Russians, Dutch, and Chinese, thus enriching Japan. Trade with the Russians would also help provide further intelligence & information about Russia and European developments for the shogunate, he argued, going on to suggest more liberal trade policies for the rest of the realm's ports as well.
A report from a Hungarian adventurer named Mauritius Augustus Count de Benyowsky had reached shogunate officials two years earlier, claiming that Russia was preparing a naval assault against Matsumae han. This turned out to be untrue, but it nevertheless stirred up concern among many samurai officials. It is unclear whether Kudô would have ever seen the document, but by virtue of interactions with members of the Dutch East India Company based in Nagasaki, he possessed a certain awareness of the international situation; this 1783 memorial claimed that Matsumae authorities were engaging in unofficial trade with the Russians, and though he provided little hard evidence, this, combined with writings in a similar vein by Hayashi Shihei, ultimately spurred Tairô Tanuma to send a mission to Matsumae in 1785 to investigate the situation. Unlike Hayashi Shihei, who was arrested for publishing his writings, Kudô was careful to not circulate his memorial publicly, but rather to give it directly to only the right people; he presented it to Miura Shôji, one of Tanuma Okitsugu's top retainers, who then passed it on to kanjô bugyô Matsumoto Hidemochi, who after consulting Tanuma ordered Matsumae to provide a series of reports on trade with Russia; this, in turn, later led to the 1785 investigative mission.
Kudô's daughter Tadano Mazuku wrote of her father and his family in a memoir entitled Mukashi banashi ("Tales of Times Past"), completed in 1812. Due to the deaths and/or lack of capability of Kudô's sons, the family line died out in that generation.
- Robert Hellyer, Defining Engagement, Harvard University Press (2009), 87-88.
- Mitani Hiroshi, David Noble (trans.), Escape from Impasse, International House of Japan (2006), 5.; John Whitney Hall, Tanuma Okitsugu (1719-1788): Forerunner of Modern Japan, Harvard University Press (1955), 102-103.
- Hellyer, 102-103.
- Marcia Yonemoto, The Problem of Women in Early Modern Japan, UC Press (2016), 214.