"Obama Castle" is the name of not one but two different Japanese Castles. "Obama" means "little beach" in Japanese.
Obama Castle, Fukui Prefecture
Obama Castle in present-day Fukui Prefecture in central Japan was the castle from which the feudal domain of Obama was ruled during the Edo period. Obama Castle was a "flat pains castle" constructed in 1601 by the warlord Kyōgoku Takatsugu, who had been given the surrounding regions as a fief by Tokugawa Ieyasu in thanks for his support of Ieyasu during the decisive Battle of Sekigahara in 1600. To build the castle, Kyōgoku drafted local fisherman and forced them to construct the castle by hand, one stone at a time.
In 1634, the Kyōgoku clan was ordered by the bakufu to move to Izumo, and the fief of Obama was awarded to Sakai Tadakatsu. Tadakatsu significantly spruced up the castle, constructing a central donjon an impressive 29 meters in height, which was completed in 1636.
Obama castle and Obama domain remained in the Sakai family for several hundred years, until the Meiji Restoration of 1868. After the feudal domains were abolished, the castle was briefly used as a prefectural office, but then the largely wooden castle burned down in a fire in 1871.
Today the castle ruins, with its impressive stone foundations remain a major tourist attraction of the town of Obama, Japan.
Obama Castle, Fukushima Prefecture
Obama castle in present day Fukushima Prefecture in northwestern Japan was a "mountain castle" constructed by the Ōuchi clan in the mid 1500s, as part of a pair of castles along with Miyamori Castle, located two kilometers to the south. The castles were designed and laid out so that each castle would help protect the flank of the other.
In 1584, when the teenaged Date Masamune took control of the powerful Date clan of nearby Sendai domain, the Ōuchi initially declared their loyalty to him, only to break away one year later and switch their allegiance to the Ashina clan. Masamune, then only 19 years old, led his army forth and crushed the Ōuchi. Taking possession of the two castles, Masamune lived in Obama castle for the next year and used it as his base of operations for further attacks against another rebellious clan, the Sadatsuna.
Thereafter the castle passed between a number of clans loyal to the Date. In 1591, Gamō Ujisato took over the castle and rebuilt it to the latest specifications, adding the stone walls and foundations still visible today. The castle changed hands a few more times thereafter, and once the peaceful Edo Period dawned the castle was no longer needed for defensive purposes, and was not large enough to be a comfortable home, so it was abandoned in 1627.
Today the castle ruins are the centerpiece of a historical park in the town of Nihonmatsu in Fukushima Prefecture, Japan.