Lifespan: Tenbun 23 (1554) to 7/26 of Keichō 12 (1607)
Rank: bushō, daimyō
Title: Junior Fifth Rank (Lower), Governor of Nagato, Master of the Outer Palace Guards of the Left Division
Lord: Tokugawa Ieyasu → Tokugawa Hidetada
Father: Ishikawa Ienari
Siblings: Yasumichi, Naritsugu, sister (formal wife of Ōkubo Tadachika), sister (formal wife of Honda Yasushige)
Wife: [Formal] Daughter of Uemura Iesada
Children: Tadayoshi, daughter (formal wife of Naitō Nobumasa), daughter (formal wife of Matsudaira Ienori), daughter (formal wife of Minagawa Takatsune)
Adopted Children: Daughter (formal wife of Yamaguchi Shigenobu) (adopted daughter of Ōkubo Tadachika)
Ishikawa Yasumichi served as a bushō and daimyō from the Sengoku to early Edo periods. He was the first lord of the Mino-Ōgaki domain and the first head of the Ishikawa family of the Ise-Kameyama domain.
In 1554, Yasumichi was born as the eldest son of Ishikawa Ienari. He was the elder cousin of Ishikawa Kazumasa.
In 1573, Yasumichi served valorously in battle against the Takeda army led by Takeda Katsuyori. In 1580, after the retirement of his father, Ienari, Yasumichi inherited the headship of the clan. Ienari was a cousin of Tokugawa Ieyasu and became the hatagashira, or leader of the band of bushi, in the western portion of Mikawa Province. He was also one of the most senior retainers in the Tokugawa family. In 1590, after Ieyasu moved his base of operations to the Kantō, Yasumichi was recognized for his prior contributions on the battlefield with a fief of 20,000 koku in Naruto in Kazusa Province.
As an influential daimyō in the Tokugawa family, Yasumichi, along with Ii Naomasa, Honda Tadakatsu, Sakakibara Yasumasa, and Hiraiwa Chikayoshi, severed on a rotation to protect Ieyasu while he was staying in Kyōto. In 1600, at the Battle of Sekigahara, Yasumichi cooperated with Matsudaira Iekiyo to defend Kiyosu Castle in Owari Province and joined in the siege against Ishida Mitsunari at Sawayama Castle in Ōmi Province. After the war, as recognition for his contributions, Yasumichi was transferred to the Mino-Ōgaki domain with a larger fief of 50,000 koku.
In 1607, Yasumichi preceded his father in death by illness at the age of fifty-four. His son, Ishikawa Tadayoshi, was still young at the time so Yasumichi’s father resumed his position as the head of the Ishikawa family but, two years later, he died in 1609. Ienari was succeeded by his nephew, Ishikawa Tadafusa.