When and how was Tokyo designated as the capital of Japan?

Through the Meiji Restoration, the Tokugawa shogunate (feudal government) turned its power over to the emperor in 1867, and in 1868 a new government was formed around the Emperor Meiji.
Edo, the castle town of the feudal government, was designated as the headquarters of the new government and its name was changed to Tokyo, which literally means "eastern capital."
However, because Japar's most important political. economic and cultural functions are today thought to be overly concentrated in Tokyo, suggestions have been made to move the Diet and various administrative organs of sovernment away from Tokyo.
The three regions proposed are Tohoku (specifically Miyagi, Fukushima. Ibaragi, and Tochigi prefectures), Tokai (Shizuoka, Aichi, and Gifu prefectures), and Kinki (Mie, Shiga, Kyoto, and Nara prefectures).