Odani Castle

Azai Sukemasa, founder of the Azai clan's rise to power in northern Omi Province, establishes the first fortifications on Odani Mountain as the clan's base of operations. Over the following decades, the Azai expand their control and the castle grows in complexity.

Azai Nagamasa inherits leadership of the clan and expands Odani Castle into a sophisticated multi-compound mountain fortress. Under Nagamasa, the Azai reach their peak power, controlling much of northern Omi Province and commanding the critical routes between Kyoto and the Hokuriku region.

Oda Nobunaga marches on Kyoto to install Ashikaga Yoshiaki as shogun. To secure the northern flank of his campaign, Nobunaga gives his younger sister Oichi in marriage to Azai Nagamasa, sealing an alliance between the two clans. Odani becomes the home of one of the most famous women in Japanese history.

Azai Nagamasa breaks with Nobunaga when Nobunaga moves against the Asakura clan of Echizen — the Azai's longtime allies. Nagamasa honors his prior obligation and sides with the Asakura against his own brother-in-law, triggering years of brutal warfare. Before doing so, he reportedly sent a messenger warning Oichi's brother of the betrayal, allowing Nobunaga to escape ambush.

Nobunaga defeats the Asakura clan in Echizen, then turns south to besiege Odani. After months of isolation and the fall of the outer compounds, Nagamasa negotiates the evacuation of Oichi and their children before the final assault. Azai Nagamasa commits suicide. His skull, according to later accounts, was lacquered in gold and used as a sake cup by Nobunaga.

With Nagamasa's death, the Azai clan is extinguished. Nobunaga gives the northern Omi domain to Toyotomi Hideyoshi (then still known as Kinoshita Tokichiro), who builds Nagahama Castle on the lakeshore below — a deliberate contrast to Odani's mountain austerity. Odani is abandoned and falls into ruin.