上総国
Aoyama Munetoshi was the eldest son of Aoyama Tadatoshi, the "daimyō" of Iwatsuki Domain (Musashi Province) and later Ōtaki Domain (Kazusa Province). In 1623, his father fell out of favor with "Shōgun" Tokugawa Iemitsu, and was exiled to Kōza District in Sagami Province.