Database: Otsu

Although the location in Ōmi province is certainly the most famous, Ōtsu was originally a common word for "large port," a place name that existed all over Japan. Ōmi's Ōtsu was particularly significant because it served as an outer port to the capital, allowing goods from Ōmi, as well as regions across the Sea of Japan, to be transported to Kyoto via the Lake Biwa waterway. Ōtsu thus prospered as a port city.

Ōtsu was primarily controlled by two conflicting factions: Onjō-ji (one of the two main temples of the Tendai school, after its schism in the 9th century) and Enryaku-ji (whose Shinto priests are known to have conducted commercial and financial activities in Ōtsu starting in the 12th century).

There were many warehouses that facilitated the transport of goods across Lake Biwa and Kyoto, as well as transporters loading and transporting goods on horseback that regularly used the route through the mountains to the capital. Oda Nobunaga, recognizing the economic power and importance of Ōtsu, received a reward from Ashikaga Yoshiaki after visiting Kyoto with him in 1568, and attempted to add Ōtsu under his direct jurisdiction, along with Sakai and Kusatsu.