After 6 years, Mamiya Rinzo(間宮林蔵), a famous explorer and a secret agent for the Shogunate, found out about the contraband trade in Hamada while he was investigating a similar crime in the Satsuma Domain(薩摩藩). For their illegal activities, Yaemon and Sahei were executed, and Okada and others committed suicide.
Though Hachiemon committed an act of treason, he was still highly respected by the local people of Hamada for being a seafaring man who saved Hamada from financial destitution. The picture on the right shows a monument erected in honor of Aizuya Yeamon in 1935. The epitaph on the monument was written by former prime minister and admiral, Okada Keisuke (岡田啓介).
The 1836 incident is important in the Dokdo/Takeshima debate because it shows that though travel to Takeshima (Ulleungdo) was banned, travel to Matsushima (Liancourt Rocks) was apparently not banned since Hachiemon traveled to Takeshima under the pretense of going to Matsushima. Some Korean historians claim that Japan had previously given up claim to both Ulleungdo and Liancourt Rocks, but the 1836 incident is evidence that that was not the case.
The following are two parts of Hachiemon's testimony, as recorded in the document of the 1836 incident , "Chronicles of the Takeshima Incident" (「竹嶋渡海一件記 全」), which is owned by and stored at Tokyo University Library (東京大学図書館所蔵). You can read the parts in Japanese here.
One day in August 1831, I took a letter of my idea (内存書) to the fiinancial officer of Hamada Domain, Mr. Murai Ogiemon (村井荻右衛門), who was stationed in Edo (江戸：Tokyo). In that letter, I wrote the following:"There is another small island called Matsushima (Liancourt Rocks) 70 to 80 ri north of Iwami (石見), and I think that it is regrettable to leave alone these two completely vacant islands, Takeshima and Matsushima. If we harvest the trees of the island or fish, it would benefit not only me, but also the nation (Hamada). We can discuss the percentage of commission for Lord Suoh (周防守：Matsudaira Yasuto) later, but I hope we can make an informal agreement first."
I asked Hashimoto to get permission from Chief Retainer Okada (岡田), so that I could make a voyage. I received a letter from Mr.Murai in Edo. It said that I should not go to Takeshima (Ulleungdo) since it was not decided if it belonged to Japan or not. Since I did not expect that kind of reply, I was disappointed and asked Hashimoto again to take the letter to Mr. Okada, so that we could get permission from him. Later, I went to Hashimoto's place to see how things went, and he told me that Mr. Murai's letter must have been implying that we go to Matsushima instead of Takeshima. He also said that Matsushima was probably too small to make a large profit, so we should just tell the officials of Hamada Domain in Edo that we were going to Matsushima (Liancourt Rocks), but go to Takeshima, instead.
The fief of Hamada had rice yields of only 55,400 Koku (石), yet the feudal lord of Hamada, Matsudaira Suohnokami Yasuto (松平周防守康任), spent a great deal of money in his quest to become a Shuza Rouju (首座老中: leading elder) in the Shogunate (Bakuhu). This left Hamada in financial hardship, which led Okada Tanomo to tacitly allow Hachiemon to engage in his illegal, yet profitable, contraband trade, even though they knew it to be against the Shogunate's policy of isolationism or sakoku (鎖国).
The feudal lord of Hamada, Matsudaira Yasuto(松平康任), started his political career as an Usher between the Daimyo and Shogunate in 1812, and in 1834, became a highest-ranking Samurai of the Shogunate, Shuza Rouju (首座老中: leading elder). He was involved in the "Sengoku Incident" (仙石一件), which was a fued with his relatives in Feudal Izushi. Because of that incident and the contraband incident, his political rival, Ohkubo Kaganomori Tadazane (大久保加賀守忠眞), and others held Yasuto responsible and had him resign from the Rouju in 1936 and confine himself up in his home until he died in 1841. Another rival was Mizuno Tadakuni (水野忠邦), who became a leading politician and who instituted the famous Tenpo Economic Reforms (天保の改革).