Allying his forces to Tokugawa Ieyasu six years later at the Battle of Sekigahara, he was subsequently awarded with the 24,000 koku Ashimori Domain.

As his brother Yukinaga died heirless in 1613, Nagaakira succeeded him, becoming daimyō of Wakayama Domain.

In the summer of 1615, Toyotomi Hideyori's Western Army moved to attack Asano's castle at Wakayama.

In 1619, he was granted the lordship of Hiroshima Domain in Aki Province, which would be the home of the Asano family until the Meiji Restoration.

[3] Nagaakira was married to Furihime, the widow of Gamō Hideyuki and third daughter of Tokugawa Ieyasu.