During this time, Kimura learned about the latest naval technology from Dutch instructors Pels Rijcken and Willem Huyssen van Kattendijke.

With the closure of the Nagasaki training center in 1859, Kimura returned to Edo and was promoted to a newly created position, magistrate of warships (Japanese: 軍艦奉行, romanized: Gunkan-bugyō), often translated as "Admiral".

[5] As commander, Kimura was able to personally select some members of the mission, including Katsu Kaishū, former head instructor at the Nagasaki training centre, who he appointed as captain of the Kanrin Maru; Nakahama "John" Manjiro, one of the few Japanese people to speak good English at the time, as translator and interpreter; and a young Fukuzawa Yukichi as an attendant.

[6] The Kanrin Maru set sail from Uraga on 9 February 1860, and arrived in San Francisco 37 days later, well ahead of the Powhatan, as the other ship had made a stop in the Kingdom of Hawaiʻi.

[9] The official embassy arrived in San Francisco aboard the Powhatan on 29 March, and were received with similar acclaim, but left for Washington D.C. on 7 April, while the Kanrin Maru was still undergoing repairs.