During the Tokugawa bakufu, Japan’s foreign policy was under set conditions, generally known as sakoku , meaning ‘closed country’. However, the existing regime was not fully closed to the outside world. Contact with foreigners in Nagasaki, Tsushima, and Ryūkyū Islands meant that the country was not completely isolated, but rather experienced a situation in which government policy was aimed at achieving strict control over all contact with the outside world, as part of a larger strategy to monopolize all foreign relations. This paper examines the ideas of Takashima Shirōtayu Shūhan (1798–1866), one of the early Japanese reformers, who argued for the modernization of Japan. Beginning in the 1830s, a Nagasaki bakufu official, Takashima Shūhan, began importing flintlock pistols, known as gewehr rifles, from the Netherlands. Additionally, through the Dutch at Dejima, Takashima managed to obtain cannons, field guns, and mortars, in doing so highlighting the importance of the modernization of the artillery forces of the bakufu army. In September 1840, Takashima Shūhan completed his memorandum, which was sent to the bakufu top administers. On 27 June 1841, Takashima was permitted to undertake the first modern Western military demonstration in Tokumarugahara (an area north of the capital city, Edo). He was heavily criticized by many, including bugyō Torii Tadateru, Torii Tadateru 鳥居忠耀 (1796–1873), metsuke 目付 (censor or inspector) and minami machi bugyō 南町奉行 (magistrate of the southern part of Edo) in the bakufu administration, was one of most active figures during the time of the Tenpo reforms, well known for his actions against people who had a strong interest in Western culture and military arts. and was placed under investigation and house arrest on charges of subversion and conspiracy. Takashima’s memorandum requires careful study in order to discover the reasons for the bakufu’s response, which must also include a discussion of the Japanese financial situation at that time.