Omi no Miya (近江宮)
Imperial Palace Omi Otsu no Miya (近江大津宮) refers to the Imperial palace where the Emperor Tenchi lived and carried out politics in the latter half of the seventh century. It is also called Omi no miya or Otsunomiya. The remained site in Nishikoori, Otsu City, Shiga Prefecture is believed to be where the Imperial Palace Omi Otsu no Miya used to be. Some points out that the name was originally written 水海大津宮 (Omi Otsu no Miya).
Background
In 660, Kudara (Baekje) was attacked by Shiragi (ancient Korean Kingdom) and Tang and fell. Kudara was an ally of Wakoku (later Japan), and Naka no Oe no Oji (later Emperor Tenchi), who was the political leader of the country at that time, dispatched troops to the Korean Peninsula in an effort to vigorously back up Kudara to restore.
In the Battle of Hakusukinoe in 663, the allied forces of Wa and Kudara were heavily defeated by the allied Tang and Shiragi, and the restoration of Kudara ended up in failure. The defeat in the War for the Restoration of Kudara was a blunder for the Naka no Oe administration, and as a result, they came to have a major fear of countries overseas. Because of that, the administration built a large number of yamajiro (castle in a mountain) and facilities for communication from the northern part of Kyushu to the coast of the Seto Inland Sea, and set up a defense facility called mizuki (water fortress) in the front line Dazaifu (local government office in Kyushu region) so that it could reinforce their defenses.
Moving of the capital
Under the circumstances mentioned above, Naka no Oe no Oji moved the capital to Otsu domain of the Province Omi on March 19, 667 (old calendar). In January 668, he ascended the throne to become the Emperor Tenchi. His ruling without official accession to the Imperial Throne had continued seven years indeed. Although the reason of such a ruling style is unknown, it can be understood that he had been caught up in handling foreign affairs and homeland security because of the defeats in foreign wars including that of the Battle of Hakusukinoe.
The reason why the capital was moved has been uncertain. The widely accepted theory is that Otsu was chosen because it was far away from Asuka where existed a strong resistance which would disturb the establishment of a new government system to counter the threats from overseas. It is also believed that the reason why Otsu was chosen as a new capital was greatly influenced by a sense of crisis on foreign affairs. In another theory, Otsu faced Lake Biwa and had access both on land and over the lake, such as Tosando Road and Hokurikudo Road, leading to various districts, which was also convenient to go westward. In case that foreign troops came up east through the Seto Inland Sea to land on Kinai region, Otsu would have been the most convenient location to evacuate from.
According to Nihonshoki (Chronicles of Japan), because the people were extremely unhappy about the moving of the capital, there were fire breakouts regardless of day or night (It is presumed that there was such a custom at that time that they set fire to the palace when the people were unhappy about politics.)
Fall of the capital
It is believed that, after Emperor Tenchi died in 671, his son Emperor Kobun succeeded him in the Imperial Palace Omi Otsu no Miya (The legitimacy of his succession to the throne as well as that of Emperor Tenmu have been the focus of controversy since the Edo period.)
According to Nihonshoki, Prince Oama (later Emperor Tenchi) was to ascend the throne, who escaped eastward from Yoshino in June 672 to base in Mino no Kuni where he commandeered troops and advanced toward the Imperial Palace to challenge the OTOMO side to a battle in July of the same year. This is the Jinshin War.
The OTOMO side was defeated while Prince Oama, who won the battle, ascended the throne to become Emperor Tenmu and built Asuka Kiyomigahara no miya Imperial residence in Asuka. The Imperial Palace Omi Otsu no Miya lasted only a little more than five years. In Manyoshu (Collection of Ten Thousand Leaves), KAKINOMOTO no Hitomaro left a poem in which he longed for the past when he visited the Palace after the fall of the capital: "A cove in Shiga stagnates, yet, wish to see people in the past again."
After that, the remained site was called "furutsu (meaning an old port)," but the original name Otsu was restored right after the moving of the capital to Heian-kyo by the imperial decree issued (on December 8, 794) by Emperor Kanmu (great-grandson of Emperor Tenchi.)
Omi-kyo
In Nihonshoki, Emperor Tenchi's capital of Omi is called "Omi-kyo," but there can be found no description of a street plan of ancient capital which existed in Heijo-kyo or Heian-kyo or no confirmation about the existence of "kyoiki" (capital area) as a special administrative district.
Omi-kyo' is believed to mean 'Omi no Miyako (capital).'
Since historian Sadakichi KIDA believed in the existence of a street plan and began using the word "Otsu-kyo" never mentioned in historical documents during the Meiji period, historical geographers and archaeologists started to use this word. Now, even historians who deny the existence of the street plan use the word "Otsu-kyo," making the concept and definition of the word blur very much, which confuses historical study.
Although Nishiotsu Station of West Japan Railway Company Kosei Line was renamed "Otsu-kyo Station" in March 2008 as petitioned by the local autonomous body, it is pointed out that further misunderstanding and confusion about the term "Otsu-kyo" and its concept might arise (Refer to the discussion on the renaming of Otsu-kyo Station for details).
The Omi period
The Omi period refers to the period of time from 667 when Emperor Tenchi located the capital in the Imperial Palace Omi Otsu no Miya until 672 when Prince Otomo (Emperor Kobun) was destroyed in the Jinshin War. Its name is derived from the Imperial Palace Omi Otsu no Miya where the capital was located. This period is also called the era of Emperor Tenchi because the reign of Emperor Tenchi almost coincides with this period.
Current status
Thanks to the Otsu City's excavation and research of Nishikoori remains, the site has been believed certain as the remained site of the Imperial Palace Omi Otsu no Miya and has been designated as a country's historic spot since 1979. The site is located in the middle of an overcrowded residential area near Omijingumae Station of Keihan Ishiyama-Sakamoto Line.