Lifespan: Tenbun 13 (1544) to Genna 5 (1619)
Clan: Kōsokabe → Nakayamada
Father: Kōsokabe Hidemichi
Mother: Daughter of Hosokawa 宗桃
Siblings: Yasuyoshi, Hidemasa
Wife: [Formal] Adopted daughter of Ichijō Kanesada
Children: Hidenaga (?), Nobutoki (?)
Adopted Children: Hidemasa
Nakayamada Yasuyoshi served as a bushō from the Sengoku to early Edo periods. He was a retainer of the Kōsokabe clan of Tosa Province.
In 1544, Yasuyoshi was born as the eldest son of Kōsokabe Hidemichi, a kokujin, or provincial landowner, in the southeast portion of the Kami District of Tosa Province. He had a younger brother named Hidemasa.
On 10/21 of Kōji 2 (1556), after his father, Hidemichi, was assassinated by his uncle, Kōsokabe Chikahide, Yasuyoshi was taken in by the family of Hosokawa 宗桃 (the original family of his mother). However, having regretted the murder of Hidemichi, Chikahide called Yasuyoshi to his place of retirement. Before long, Yasuyoshi moved to Nakayamada where he had landholdings. Later, after Kōsokabe Chikayasu inherited the family, he deferred by changing his surname to Nakayamada. Thereafter, he dutifully served as a chief retainer for Chikayasu and, after the demise of Chikayasu, served as a guardian for his orphan, Kōsokabe Sadachika. After the Battle of Sekigahara in 1600, Chōsokabe Morichika was removed from his position. Yasuyoshi served the new landlord named Yamauchi Kazutoyo. Known as quiet, polite, and having both wisdom and courage, Yasuyoshi was a respected individual. He died on 1/22 of Genna 5 (1619).