Inazu Shigemasa served as a bushō during the Azuchi-Momoyama period. He was a retainer of the Hyūga-Itō clan. Shigemasa served as the lord of Kiyotake Castle in the Miyazaki District of Hyūga Province.
The Inazu were an illegitimate branch of the Itō clan. When Itō Ujisuke came to Hyūga, the Inazu accompanied him and became servants of the Itō. Shigemasa’s abilities were recognized from an early age and, at nineteen, he became a servant of his lord, Itō Suketake. He deployed for the Keichō Campaign on the Korean Peninsula and, in 1598, was appointed as the lord of Kiyotake Castle and selected as a chief retainer by Suketake.
Siege of Miyazaki Castle
In 1600, after the conflict between Ishida Mitsunari and Tokugawa Ieyasu intensified, upon orders of his lord, Suketake, who was in Ōsaka at the time, his lineal heir, Itō Sukenori, was sent back to Obi in Hyūga and, through the maneuvers of Suketake, Miyagawa Hanzaemon, the truce bearer of Kuroda Yoshitaka, was dispatched to Obi. Shigemasa consulted with Hanzaemon and, as evidence of his support for the Eastern Army, made plans to capture Miyazaki Castle defended by Takahashi Mototane who was aligned with the Ishida.
On 9/29, Shigemasa, serving as the commander-in-chief, led 3,000 troops from the Itō army to assault Miyazaki Castle. Out of the 3,000 troops, Shigemasa separated 1,500 of them and then further divided them into five battalions, each with 300 men, sending them to capture Miyazaki Castle, along with 500 men to Kiyotake Castle, and the remainder to make provision for Tano and Shihasuzaki castles. Miyazaki Castle was defended by a garrison of 700 soldiers under Gondō Tanemori. Owing, however, to the skillful command of Shigemasa, the Itō army toppled the castle in one day. This is known as the Siege of Miyazaki Castle. This battle led to a temporary conflict between the Itō and Shimazu clans. Thereafter, Shigemasa engaged in approximately fifty skirmishes in Sadowara, Mukasa and other locations to defend Miyazaki Castle.
On 10/18, when over 2,000 troops from the Shimazu army launched an offensive from the directions of Uryūno and Sadowara, 1,100 soldiers from the Itō army defeated them. On 10/30, when 3,200 soldiers from the directions of Mukasa and Kuraoka launched another offensive, less than 1,000 soldiers from the Itō repelled them. On numerous occasions, Shigemasa repelled or routed the Shimazu army. Having protected Miyazaki Castle over a period of seven months, Shigemasa became known in the area for his military prowess.
Upon the fall of Miyazaki Castle, Takahashi Mototane had pledged allegiance to the Tokugawa and received recognition of his rights to his landholdings, so Miyazaki Castle was returned to him. As a result, Shigemasa gradually became isolated in the family which only accelerated after the death by illness of Itō Suketake and his replacement by Sukenori. His behavior started to become erratic while Sukenori, the lord of the domain, prepared written inquiries and attempted to have Shigemasa dismissed. Shigemasa, however, refused to listen and finally was ordered to commit seppuku. On 10/12 of Keichō 7 (1602), Shigemasa responded by holing-up with a small group in Kiyotake Castle, but was attacked by soldiers from the Obi domain and, on 10/18, was killed in action in an event known as the Inazu Revolt. He was twenty-nine years old.
According to a historical account of Hyūga, during the siege of Miyazaki Castle, Shigemasa borrowed a prized horse from Sukenori. Nagakura Miyoshi headed-out as a messenger to demand the return of the horse, but Shigemasa cursed Miyoshi on the grounds that he intended to return the horse at a time of his own choosing when the situation settled down. Owing to Shigemasa’s rudeness despite having come simply as a messenger of Sukenori, Miyoshi drew his short sword and slashed at Shigemasa but Shigemasa fled to an inner room while a retainer, Aman Sanpei, came running and killed Miyoshi. After hearing this story, Yamada Munemasa, Matsura Kyūbei, and Nagakura 戎祐 held a secret meeting and reported to Sukenori’s mother, Shōjuin, whereupon Shōjuin ordered that Shigemasa be executed. After learning of these developments, Shigemasa took a hostage and holed-up in Kiyotake Castle.
According to one account, Miyagawa Hanzaemon who came as a truce bearer of Kuroda Josui praised Shigemasa, noting: “The tactics of Kamon-no-suke (Shigemasa) and bravery of the bushō from the Itō family resemble the Tachibana family in Tsukushi (the provinces of Chikuzen and Chikugo).” After hearing from Miyagawa Hanzaemon and others in regard to the battle at Miyazaki Castle, Kuroda Josui summoned all of his attendants and extolled the actions of the Itō army in saying “Use the conduct of the Itō army in battle as a model.”