Lifespan: 15xx to sixth month of Eiroku 4 (1561)
Other Names: Nagato-no-kami
Lord: Oda Nobunaga
Father: Iwamuro Shigetoshi (Iga-no-kami) or Iwamuro Munenobu (Nagato-no-kami)
Siblings: Shigeyasu, Shigeyoshi
Children: Kojūzō, daughter (wife of Katō Yasaburō) (?)
Iwamuro Shigeyasu served as a bushō during the Sengoku period. He was a retainer of the Oda clan.
Shigeyasu was born as the son of either Iwamuro Shigetoshi (Iga-no-kami) or Iwamuro Munenobu (Nagato-no-kami). If he was the son of Munenobu, then he would have been associated with the Iwamuro clan known as one of the Fifteen Families of Kōka.
From early on, Shigeyasu served Oda Nobunaga. In 1559, he was selected as a member of an elite cavalry known as the akahoroshū. The members rode with red capes that filled with air to deflect arrows or objects hurled at them in battle.
He continued acting as a servant to Nobunaga.
In the fifth month of 1560, Yoshiyuki joined Sawaki Yoshiyuki, Hasegawa Kyōsuke, Yamaguchi Hida-no-kami, and Katō Yasaburō on a rapid pre-dawn deployment with their lord, Nobunaga, for the Battle of Okehazama. Shigeyasu, Sassa Masatsugu, Senshū Suetada preceded the main division of Nobunaga, and, with a battalion of 300 troops, clashed with the Imagawa army. Masatsugu and Suetada were killed in action, but Shigeyasu managed to survive the combat.
Thereafter, he continued to serve Nobunaga. In the sixth month of 1561, Shigeyasu helped suppress a rebellion by Oda Nobukiyo, the lord of Inuyama Castle. While aiming to capture Oguchi Castle defended by Nakashima Bungo-no-kami (an ally of Nobukiyo), Shigeyasu attempted to lure him to his side but Bungo-no-kami refused. This resulted in the Siege of Oguchi Castle and, during this battle, he was pierced in the temple by a spear and died.
After the death of Shigeyasu, one of his fellow bushō, Katō Yasaburō, became a son-in-law and adopted the name of Iwamuro Kanemon, but whether he succeeded to the headship of the clan is unknown. There is a theory that he had a son named Kojūzō.
Iwamuro Yoshiyasu (the son of Shigeyoshi who, in turn, was the second son of Shigetoshi) served the Arao clan who were chief retainers of the Ikeda clan of the Tottori domain which governed Inaba and Hōki provinces in the Edo period. His great-grandchild, Iwamuro Munekata, became a rōnin, or wandering samurai, and went to Kyōto to become a doctor. His daughter named Tsuru became an attendant to the Imperial Princess Shigeko (the fifth daughter of Emperor Nakamikado). After the princess wed Prince Kanin-no-miya Sukehito, Tsuru was also cherished by the prince, and gave birth to three princes, beginning with Emperor Kōkaku.
Ōta Gyūichi, the author of the authenticated biography of Nobunaga known as the Shinchō-kōki wrote that “Shigeyasu was a clear genius and Nobunaga greatly lamented his demise,” evidencing that he was highly respected by Nobunaga and within the Oda family.