imperial reign; period
Refers to the reign of an emperor or a historical period named after an emperor. Often used in historical or formal contexts.
The Meiji period was an era when Japan's modernization advanced.
This shrine is said to have been built during the reign of the previous emperor.
治世 also means reign, but is more commonly used for any ruler's reign, not exclusively imperial.
Standard kanji spelling for imperial reign or period.
Alternate kanji spelling, also used for imperial reign.
Compound of 御 (honorific prefix) and 代 (age, era). The reading みよ is a native Japanese reading (kun'yomi).