Akaike Nagatō served as a retainer of the Sagara clan of Higo Province.
Nagatō entered Ōkuchi Castle as one of the leaders, serving as the commander of the Hitoyoshi-shū, or a group of senior retainers of the Sagara clan, together with 1,000 foot soldiers.
In 1564, the Sagara joined forces with the Itō clan, resulting in a deterioration of relations with the Shimazu clan and fierce attacks against Ōkuchi Castle. Although Nagatō was ordered to stiffly defend the castle, on 2/21, he attempted to launch a field battle. Kuwahata Shinroku and Iwasaki Rokubei led a contingent of over 300 men including 65 mounted soldiers to Hazu-ga-o. The soldiers set fire to the area to draw out the Shimazu forces, but lost and retreated to Ōkuchi. Nagatō and Okamoto Yoriuji were injured while fighting in the rear guard, while Kuwahata, Iwasaki, and many others perished in battle.
On 4/9 of 1567, Niiro Tadamoto came out of Ichiyama Castle to greet a messenger from Shimazu Yoshihisa, a sengoku daimyō from Satsuma Province, whereupon Nagatō directed Uemura Yakurō, Matoba Gotōsaemon, and others to launch a surprise attack at Hatsukuri. The forces pursued Tadamoto to Ichiyama Castle, battling against the Shimazu with lances at the entrance to the castle.
On 1/20 of 1568, Nagatō joined with members of the Hishikari clan to repel an attack by the Shimazu at Ōkuchi Castle, placing Shimazu Yoshihiro in a predicament. In this battle, Yoriuji contributed to the cause by injuring Kawakami Hisaaki, leading to his later death.