Kutsuki Masatsuna (朽木 昌綱, March 5, 1750 – May 18, 1802), also known as Kutsuki Oki-no kami Minamoto-no Masatsuna, was a hereditary Japanese 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. His childhood name was Tomojiro (斧次郎). Masatsuna 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).