Ono Otsū (小野お通, 1559 or 1568 – 1631), also known as Ono no Ozū, was a Japanese noblewoman, calligrapher, poet, painter and musician. She was a student of the arts in Kyoto, studying painting, calligraphy, music, chanting, and waka poetry. Her work was noticed by members of the Tokugawa shogunate, including Tokugawa Ieyasu and Tokugawa Hidetada, and she was often hired by them to teach members of their court. Because she was the author of works that impacted Japanese art during the Azuchi-Momoyama and Edo period, and served several prominent figures, Otsū was proclaimed one of the leading female calligraphers of premodern Japan.