Bansha no goku (Imprisonment of scholars of Western learning) (蛮社の獄)

Bansha no goku was the suppression of free speech that occurred in May 1839.

Shoshikai (salon, a think tank)
Feudal retainers of Tahara domain, Kazan WATANABE, Choei TAKANO and Dutch scholar Sanei KOSEKI organized Shoshikai (association) with interested people like town doctors, feudal retainers of domain and vassals of shogun in order to study Western learning and internal and external situation for the purpose of coastal defense, and scholars of Japanese literature named the organization as Bansha, which has the disdainful meaning "Kessha (association) studying Yaban (barbarous) Western science." However, this was not the suppression of Shoshikai, but was the oppression of some relevant people in Shoshikai (the leader of Shoshikai, Katsusuke ENDO, was not punished).

Choei TAKANO, learning about the Morrison incident, opposed the edict to repel foreign vessels issued by the bakufu (Japanese feudal government headed by a shogun) in his book 'Bojutsu yumemonogatari.'
Yozo TORII, the bakufu's metsuke (inspector of foot soldiers), hostilely viewed his opposition and targeted Shoshikai as he had heightened the sensitivity due to Oshio Heihachiro no ran (Rebellion of Oshio Heihachiro). In addition, when Torii argued with Hidetatsu EGAWA, the Shogun's retainer and a member of the Shoshikai, over the survey method of Edo Bay, Torii was defeated by Egawa, who utilized Kazan WATANABE's connections and knowledge of Western science. As a result, Torii was given a reprimand by the roju (senior councilor) Tadakuni MIZUNO, and Torii regarded Egawa as a political rival.

Arrests and punishment
At first, there was an internal leak from Shoshikai saying 'someone is planning to travel abroad.'
In spite of the low credibility of the leak, it became an incident; hence, it is said that this accusation itself was a plot developed by Torii.

Kazan WATANABE was arrested and Choei TAKANO surrendered himself to the police. Sanei KOSEKI committed suicide before being arrested. Townspeople in Shoshikai died from disease during the investigation.

Kazan WATANABE was put in prison in Denmacho town for criticizing the bakufu in 'Shinkiron' (personal document criticizing the bakufu) and then was confined to his house (later committed suicide), and Choei TAKANO was sent to prison. Shinkiron' had not been published and only the draft was discovered during a house search.

This was not a suppression of Dutch scholars by the Bakufu conservatives or Confucian scholars, but the truth was that Torii, who perceived Shoshikai as an enemy, acted solely with other cabinet officials with the Shogunate's approval. This incident had been considered as a suppression of Western learning for a long time even though there were just more than a dozen arrestees, because "Yogakutozenshi" written by Mokichi FUJITA in the Meiji period described this incident in relation with Movement for Liberty and People's Right by parity of reasoning.