Nihonmatsu Domain was a feudal domain under the Tokugawa shogunate of Edo period Japan, located in southern Mutsu Province. It was centered on Nihonmatsu Castle in what is now the city of Nihonmatsu, Fukushima, and its territory included all of Nihonmatsu, Motomiya, Ōtama and most of the present-day city of Kōriyama. For most of its history it was ruled by the Niwa clan. The Nihonmatsu Domain was also the scene of a major battle of the Boshin War of the Meiji Restoration.

Motomiya is a city located in north-central Fukushima Prefecture, Japan. As of 1 March 2020, the city had an estimated population of 30,401 in 10,680 households and a population density of 350 persons per km2. The total area of the city was 88.02 square kilometres (33.98 sq mi). It is the smallest city in Fukushima Prefecture, both in terms of population and size.