Rittaishi (Investiture of Crown Prince) (立太子)
Rittaishi (the investiture of Crown Prince) is a ceremony prevailed in East Asia to officially designate an heir of Chinese or Japanese Emperor as Crown Prince for prospective enthronement.
Rittaishi in Japan
In ancient times, in the Japanese Imperial court, Crown Prince was also called Chokun (which was alternatively pronounced as Moke no kimi). An Imperial prince who had been designated as Chokun conventionally performed Rittaishi no Rei (ceremonial investiture of the Crown Prince) to declare both domestically and internationally that he became Crown Prince who was the heir to the Imperial throne. Before the Edo period, there was no law that determined the order in line to succession to the Imperial throne such as Imperial House Act, and Chokun, or the Crown Prince, was customarily chosen from among plural candidates, intervened by the will of the Emperor and by the court and bakufu (shogunate). However, during medieval times when the Imperial court's power declined, not a few Crown Princes ascended to the Imperial throne without the ceremonial Rittaishi due to lack of budget for the Rittaishi no Rei.
After the Meiji period, Imperial House Act was enacted as Imperial Family regulations. Thereafter, the order of succession to the Imperial throne was strictly regulated by the law, and any change in the order became unallowable unless he had serious health problems or the like. Accordingly, an Imperial prince who was the first in line to the Imperial throne began to be considered 'Imperial prince who was the heir to the throne' and appointed Crown Prince.
After the Meiji period, the Rittaishi no Rei took place four times.
Yoshihito Shinno (the term Shinno refers to Imperial Prince) (Emperor Taisho): November 3, 1889
Hirohito Shinno (Emperor Showa): November 3, 1916
Akihito (the present Emperor): November 10, 1952
Naruhito Shinno (current Crown Prince): February 23, 1991