Kunitomo Kosunaki(国友 一貫斎?, November 21, 1778 – December 26, 1840) was a Japanese gun manufacturer of the early 19th century, who, after having spent several months in Edo, where he could get accustomed with Dutch wares, built Japan's first reflective telescope in 1831. It was of the Gregorian type.
Kunitomo's telescope had a magnification of 60, and allowed him to make very detailed studies of sun spots and lunar topography. Four of his telescopes remain to this day.
Kunimoto also developed manufacturing methods for guns, and also created an air gun based on rangaku knowledge acquired from the Dutch in Dejima.