Koizumi Domain

The was a Japanese domain of the Edo period, with its headquarters within the city limits of present-day Yamato-Kōriyama, Nara. It was ruled for the entirety of its history by the branch of the Katagiri family founded by Katagiri Sadataka, a younger brother of the famed Katagiri Katsumoto. In July 1871, with the abolition of the han system the Koizumi Domain became Koizumi Prefecture, and later it was finally made a part of Nara Prefecture. 
List of lords.
The second lord, Katagiri Sadamasa (1605-73), is an important figure in the history of the Japanese tea ceremony. He founded the Sekishū-ryū school of Japanese tea ceremony, and in Japanese tea history, is usually known as Katagiri Sekishū.