Koizumi Domain

It was centered around Koizumi jin'ya in what is now the city of Yamatokōriyama, Nara and was ruled by the tozama daimyō Katagiri clan for all of its history.

[1][2][3] Katagiri Sadataka, the younger brother of Katagiri Katsumoto (who was famous as one of the Seven Spears of Shizugatake) served Toyotomi Hideyoshi and achieved military exploits in the Battle of Odawara and the Japanese invasions of Korea (1592–1598), for which he was awarded with a fief of 10,000 koku in Harima Province.

In 1614, during the incident involving the inscription on a bell sponsored by Toyotomi Hideyori at the temple of Hōkō-ji in Kyoto (which Tokugawa Ieyasu was attempting to use as a casus belli against the Toyotomi clan), the Katagiri brothers were suspected by Hideyori of secretly communicating with Ieyasu.

When evacuating from Osaka Castle, the 300 soldiers of the Katagiri clan were fully armed and made a spectacular move of lighting the matchlocks of their guns.

The eighth daimyō, Katagiri Sadanobu, was a noted tea master under the name "Shunsai", and formed his own branch of the Sekishu-ryū school.

Katagiri Sadaatsu, final daimyo of Koizumi Domain