On December 1, Princess Aiko turned 20. In Japan, people become legal adults at the age of 20. Princess Aiko's coming-of-age ceremonies, known as Seijin-shiki, took place on December 5 with a delay caused by her classes during the weekdays at Tokyo’s Gakushuin University. In the morning, Princess Aiko visited the three sanctuaries at the Imperial Palace and received the Grand Cordon of the Order of the Precious Crown from Emperor Naruhito.