Lifespan: Tenbun 21 (1552) to 9/15 of Keichō 5 (1600)
Other Names: Masachika, Chikaoki
Title: Director of the Bureau of Military Storehouses, Assistant Director of the Bureau of Military Storehouses (honorary)
Lord: Ashikaga Yoshiaki → Toyotomi Hideyoshi → Kuroda Nagamasa
Father: Itami Chikaoki (?)
Siblings: Sister (wife of Katō Shigenori, mother of Katō Yoshishige and Kuroda Kazushige)
Itami Tadachika served as a bushō during the Sengoku and Azuchi-Momoyama periods. He was a kokujn, or provincial landowner, in Settsu Province.
Tadachika is surmised to have been the son of Itami Chikaoki, the lord of Itami Castle in Settsu.
In 1568, when Oda Nobunaga marched upon the capital of Kyōto to install Ashikaga Yoshiaki as the fifteenth shōgun of the Muromachi bakufu, Tadachika pledged allegiance to Yoshiaki and received recognition of his rights to a fief of 30,000 koku in Settsu. At this time, his father, Chikaoki, was appointed as one of the Three Shugo of Settsu, in addition to Wada Koremasa and Ikeda Katsumasa. In the first month of 1569, at the Battle of Honkoku Temple, Tadachika fought against Miyoshi forces.
In the eighth month of 1570, Tadachika obeyed Nobunaga and arrived at an encampment in Tenman-no-mori in Nakajima. In 1572, he followed Sakuma Nobumori and Shibata Katsuie on a deployment to Kawachi Province. While continuing his association with the Oda forces (in support of Ashikaga Yoshiaki), he fought against Miyoshi Yoshitsugu and Matsunaga Hisahide.
After Nobunaga and Yoshiaki had a falling out, he was initially stopped by Wada Korenaga, but later allied with Yoshiaki, joining forces with his former archrivals, the Miyoshi and the Matsunaga. In 1573, following an attack by Oda forces, Tadachika vacated Kashima Castle. In 1574, he holed-up in Itami Castle, but incurred an attack by Araki Murashige and, on 11/15 of the same year, turned-over the castle again. On this occasion, his father, Chikaoki, took his own life. Thereafter, for a while, Tadachika’s whereabouts were unknown but, after the Honnō Temple Incident resulting in the death of Nobunaga, he served as a member of the umamawari, or mounted cavalry, for Hashiba Hideyoshi. Around this time, he protected relatives including Katō Yoshishige and Kōri Muneyasu from the Itami family.
In 1592, Tadachika was stationed at Nagoya Castle in Hizen Province in support of the Bunroku Campaign on the Korean Peninsula.
After the death of Hideyoshi, Tadachika affiliated with Kuroda Nagamasa and, in the ninth month of 1600, was killed in action fighting for the Eastern Army at the Battle of Sekigahara. He was forty-nine years old.