Suenaga Yarokusaemon served as a bushō during the Sengoku period. He was a retainer of the Mōri clan and, later, the Kikkawa clan. He may also have originally been a retainer of the Noma clan, kokujin, or provincial landowners, in Yano in Aki Province.
On 8/22 of Tenbun 24 (1555), Yarokusaemon was ordered by Mōri Motonari and Mōri Takamoto (father and son) to guard the stronghold of Yamasato. In the written orders, a promise was made that his descendants could also possess the land awarded for his services, suggesting that the responsibilities posed the risk of death. The same orders were given to Nishi Saneyo, Niiya Sanemitsu, and Kurata Hikogorō.
Nishi Sanyo was a former retainer of the Noma clan which was decimated in the fourth month of 1555. Likewise, Niiya Sanemitsu and Yarokusaemon may also have been former retainers of the Noma.
In the eighth month of 1555, the Yamasato area was extremely tense owing to a standoff between the Ōuchi clan (the Sue) and the Mōri after the Mōri rebelled against them. During the period, the Yamasato stronghold guarded by Yarokusaemon was subject to frequent attacks by the Sue.
Niiya Sanemitsu was also guarding the castle at this time. In the tenth month of 1556, Mōri Takamoto granted land in Yamasato to Sanemitsu as compensation.
Later, Yarokusaemon served Kikkawa Motoharu. In the sixth month of 1577, Motoharu granted him landholdings in Yoshiura of approximately two hectares and 200 square meters, five rice fields, and eight residences. Yoshiura was the former territory of the Noma clan and, during the Daiei era (1521 to 1528), an individual named Noma Gyōbu-taifu appears in records as a commander in the navy. This may refer to Yarokusaemon who was in Yoshiura and commanded the Kikkawa navy. The Kikkawa family included members who originated from retainers of the Noma as well as sailors from the Aga and Kure clans in addition to the Ashiura clan residing in Kure from the time prior to the transfer to Iwakuni.
The year of Yarokusaemon’s death is uncertain but when Kikkawa Motoharu received news of his passing, he ordered a retainer named Yamagata Echizen-no-kami to inform Yarokusaemon’s orphan, Suenaga Hikokurō, that he would engage him for his services out of compassion for the loss of Yarokusaemon.