Kutsuki Masatsuna

, also known as Kutsuki Oki-no kami Minamoto-no Masatsuna, was a Japanese daimyō of the Fukuchiyama Domain and a scholar of numismatics and Dutch studies (rangaku).

His childhood name was Tomojiro (斧次郎). Kutsuki was hereditary daimyō of Oki and Ōmi with holdings in Tanba and Fukuchiyama. His warrior clan was amongst the hereditary vassals of the Tokugawa family (the fudai) in the Edo period.

Scholarship Kutsuki was a polymath and a keen student of whatever information was available at that time concerning the West. Since most printed material was only available in the Dutch language, such studies were commonly called "Dutch learning" (rangaku).

He studied rangaku with the physician , and associated with the Dutch during their visits to Edo as well as with the interpreters at Nagasaki.

The Dutch trade official and japanologist Isaac Titsingh considered Kutsuki to have been his closest friend while he was in Japan, and their correspondence continued after Titsingh left Dejima for the last time. The oldest surviving letter from Kutsuki to Titsingh dates from 1789; and this letter mentions mutual friends such as Shimazu Shigehide (the father-in-law of the eleventh shōgun, Tokugawa Ienari) and Kuze Hirotami (Nagasaki bugyō or governor of Nagasaki port). Later Titsingh sent him Nicolas Sanson's world atlas (with the Netherlands circled in red ink), upon which Kutsuki based his studies of European geography.

Kutsuki and Titsingh shared an interest in numismatics. After Titsingh was reassigned from Japan in 1784, he sent packages of coins from India—Dutch coppers, as well as coins from India, Russia, Turkey, and Africa. Titsingh in turn received Japanese and Chinese coins as gifts.

Family Father: Kutsuki Tsunasada (1713–1788) Foster Father: Kutsuki Nobutsuna (1731–1787) Wives: Ikumanhime, Matsudaira Munenobu's daughter Honda Sukemitsu's daughter Ito Nagatoshi's daughter Children: Yuunosuke Kutsuki Tsunakata (1787–1838), adopted by Tomotsuna Yonekura Masanaga Fukuju Taro Adopted Son: Katsuki Tomotsuna (1767–1803)

Events of the daimyōs life 1781 (Tenmei 1): This numismatist scholar's book, Shinzen zenpu ("Newly selected manual of numismatics"), was published. 1782 (Tenmei 2): This numismatist scholar's analysis of copper currency in China and Japan "Shinzen zenpu" was presented to the emperor. 1785 (Tenmei 5): Masatsuna inherited his father's position and titles. 1787 (Tenmei 7): This rangaku/numismatist scholar's book, Seiyō senpu (Notes on Western Coinage), with plates showing European and colonial currency, was completed. -- see online image of 2 adjacent pages from library collection of Kyoto University of Foreign Studies and Kyoto Junior College of Foreign Languages 1789 (Kansei 1): This rangaku/geographer scholar's book, Taisei yochi zusetsu ("Illustrated explanation of Western geography"), was published. 1801 (Kansei 12): Mototsuna predeceased his father, and Masatsuna's grandson, Tsunagata becomes daimyō. 1802 (Kansei 13): Masatsuna dies.

Selected work Kutsuki's published writings encompass 8 works in 12 publications in 1 language and 25 library holdings.

1781 -- 1787 -- , also romanized as Seiyō senpu