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.
Emperor Kōkaku
In 1817, Kōkaku abdicated in favor of his son, Emperor Ninkō. In the two centuries before Kōkaku's reign most emperors died young or were forced to abdicate. Kōkaku was the first Japanese monarch to remain on the throne past the age of 40 since the abdication of Emperor Ōgimachi in 1586. He was also the last Emperor to rule as a Jōkō (上皇), an emperor who abdicated in favor of a successor (it has been announced that the current Emperor, Akihito, has plans to abdicate in 2019, however, and would thus be the first Jōkō since then). Kōkaku travelled in procession to Sento Imperial Palace, a palace of an abdicated emperor. The Sento Palace at that time was called Sakura Machi Palace. It had been built by the Tokugawa shogunate for former-Emperor Go-Mizunoo.