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 of Japan
There are two Japanese words equivalent to the English word "Emperor": "tennō" (, "heavenly sovereign"), which is used exclusively to refer to the Emperor of Japan, and "kōtei" (皇帝, the title used for all other foreign Emperors), which is used primarily to describe non-Japanese Emperors. "Sumeramikoto" ("the Imperial person") was also used in Old Japanese. The term "tennō" was used by the Emperors up until the Middle Ages; then, following a period of disuse, it was used again from the 19th century. In English, the term "mikado" ( or ), literally meaning "the honorable gate" (i.e. the gate of the imperial palace, which indicates the person who lives in and possesses the palace), was once used (as in "The Mikado", a 19th-century operetta), but this term is now obsolete. (Compare Sublime Porte, an old term for the Ottoman government.)