Emperor of Japan
The current Emperor on the throne is typically referred to as "Tennō Heika" (, "His (Imperial) Majesty the Emperor"), "Kinjō Heika" (, "His Current Majesty") or simply "Tennō", when speaking Japanese. The current Emperor will be renamed "Daijō Tennō" (, Retired Emperor), often shortened to "Jōkō" (), upon his planned retirement on 30 April 2019, and renamed "Heisei Tennō" () after his death and will then be referred to exclusively by that name in Japanese. In Japanese culture, it is considered a major faux pas to refer to a living Emperor by his posthumous name, although the posthumous name is the same as the era, which is used in official documents.
Chrysanthemum Throne
According to legend, the Japanese monarchy is said to have been founded in 660 BC by Emperor Jimmu; Akihito is the 125th monarch to occupy the Chrysanthemum Throne. The extant historical records only reach back to Emperor Ōjin, who is considered to have reigned into the early 4th century. 
In the 1920s, then-Crown Prince Hirohito served as regent during several years of his father's reign, when Emperor Taishō was physically unable to fulfill his duties. However, the Prince Regent lacked the symbolic powers of the throne which he could only attain after his father's death.