Inō Tadataka (1745−1818) was a famous surveyor and cartographer of the Edo period in Japan. He is known for completing the first map of Japan based on actual measurements, which he himself made by traveling throughout the country. In 1800 Inō surveyed the area from Edo (present-day Tokyo) to Nemuro (in present-day Hokkaidō) on the Ōshū Highway. He continued measuring other parts of eastern Japan until 1803. He compiled the results of his surveys into three sets of maps of different scales, which he presented to the shogunate in 1804. Shown here is the smallest-scale version (1:432,000). The lines radiating from the summits of mountains and from islands were used to measure the azimuth from certain fixed points; they indicate that Tadataka adopted junbō or kōkaihō, the old East Asian intersection method to determine the location of distant points by flat surveying. The two vermillion imprints of seals on the title piece and on the sheet of the map itself indicate that the work was once owned by Nakagawa Tadahide, a kanjō-bugyō (official of the Tokugawa shogunate with responsibility for finance) from 1797 to 1806.