From Samurai Revolution: The Dawn of Modern Japan Seen Through the Eyes of the Shogun’s Last Samurai, by Romulus Hillsborough (Tuttle, 2014), Kindle pp. 171-172:
As the twenty-eighth daimyo of Satsuma, Nariakira had been a radical reformer and one of the most progressive feudal lords of his time—even before Perry. He advocated “enrich the nation and strengthen the military” and embraced Western technology, namely warships and guns, to fortify Japan. He realized that the island country must open its ports to foreign trade to acquire that technology; and that the Bakufu and the feudal domains must pool their resources and cooperate with one another to tackle the dangerous problems of the encroaching modern age—all revolutionary ideas in pre-Perry Japan. This is not to say that he advocated abolishing the feudal system in favor of a unified Japanese nation. Such a notion would not be considered by even the most radical thinkers for some years to come. Rather, as daimyo of Satsuma, he planned to reform the Bakufu to give outside lords like himself an unprecedented voice in national affairs. Hisamitsu inherited those plans.
Nariakira began the drive for modern fortifications in his own backyard, radically modernizing Satsuma. In Kaei 5 (1852), the year after his accession, he began the construction of reverberatory and blast furnaces for the manufacture of warships, cannons, rifles, and other modern weaponry, and fortified the coastal defenses of Satsuma, planting mines in the sea approaches to his castle town of Kagoshima. In the Second Month of the following year—four months before Perry’s first arrival—Nariakira began the construction of the warship Shōhei Maru, the first modern ship produced in Japan. He arranged with the Bakufu for permission to build the triple-masted sailing vessel even before the ban on ocean-going ships was lifted—under the condition that it be used for the express purpose of defending the Ryūkyū islands in the south, nominally ruled by their own king but subjugated by Satsuma since the beginning of the seventeenth century.
During the countrywide debate on whether to accept Perry’s demands, Nariakira urged Edo to enter into protracted diplomatic negotiations with the Americans to stall them until Japan could prepare itself to repel the foreigners by military force. As a means to this end, he advised the Bakufu to abolish the ban on oceangoing vessels. When the ban was lifted, he manufactured more warships. He westernized the Satsuma military, training his troops in modern artillery methods. He modernized Satsuma, transforming it into the most militarily, economically, and industrially advanced entity in all of Japan, bar none—including the Tokugawa Bakufu.
Satsuma was no doubt spurred into action by Admiral Perry’s visit to Okinawa in 1852, a year before he first arrived in Edo.