Lifespan: 15xx to Genna 9 (1623)
Other Names: Hirotaka
Lord: Mogami Yoshiaki → Mogami Iechika → Mogami Yoshitoshi
Father: Mogami Yoshiaki
Mother: Shimizu-hime (daughter of Shimizu Yoshiuji)
Siblings: Mogami Yoshiyasu, Mogami Iechika, Shimizu Yoshichika, Yamanobe Yoshitada, Kaminoyama Yoshinao, Akitaka
Ōyama Akitaka served as a bushō in Dewa Province during the early Edo period.
Akitaka was born as the sixth son of Mogami Yoshiaki, the sengoku daimyō of Dewa Province and lord of Yamagata Castle. The Mogami were a prestigious family descended from the Shiba clan. The Shiba were members of the Ashikaga clan. Around the time that Akitaka was born, the Shiba were in decline while the Mogami experienced an expansion of their power.
After the Battle of Sekigahara, the Mogami became major landowners as lords of the Yamagata domain totaling 570,000 koku. Akitaka was granted Ōyama Castle with a fief of 21,000 koku. Following the death of his father, Yoshiaki, Akitaka’s older brother, Mogami Iechika, became the successor as lord of the domain. In 1615, Akitaka’s fief was increased by 27,000 koku. From around this time, the retainers of the Mogami experienced instability, and, in 1617, Iechika suddenly died and was succeeded by his son, Mogami Ienobu (later known as Yoshitoshi). Ienobu’s youth and inexperience triggered a rupture among the band of retainers, with some maintaining their support for Ienobu while others sought to replace him with Yoshiaki’s fourth son named Yamanobe Yoshitada. This struggle is known as the Mogami Disturbance. At this time, Akitaka did not ally with either his older brother, Yoshitada, or his nephew, Ienobu, and, instead, assumed a neutral stance. Later, after the bakufu removed the Mogami from their position as the lords of the Yamagata domain, Akitaka was taken in by Sakai Tadayo, but, the next year, suddenly took his own life in Hiroshima.