During the Heian period, this area was called "Nomi no Ura". In 1129, when TAIRA no Tadamori (TAIRA no Kiyomori's father) was selected as an envoy to hunt down pirates in Sanyo-do and Nankaido, this land was pacified by Tadamori. At this time, Tadamori divided his name into two, namely 'Tadanoumi' for the north shore and 'Mori' (Mori fishing port) for Omishima in the south. This is the origin of Tadanoumi. During the Kamakura period, this land was owned by the Kobayakawa clan, but at the end of the Kamakura period, it became the territory of the Ura clan, a branch family of the Kobayakawa clan. From the end of the Muromachi period to the Sengoku period, the Ura clan became the main force of the Kobayakawa Navy. The representative existence is Munekatsu Ura (Munekatsu Nomi). Munekatsu built Kagi Castle on this land as his base, and in 1581 he built Shounji Temple.