Emperor Akihito and his attendants participate in a ritual at the Kashikodokoro sanctuary within the Imperial Palace grounds as part of the process for his abdication. (Video footage provided by Imperial Household Agency)

Emperor Akihito and other imperial family members participated in a formal ceremony on April 30 that will be one of the last ones before his abdication.

At around 10 a.m., Akihito, dressed in a formal "sokutai" outfit that only the emperor may don, entered the Kashikodokoro shrine on the Imperial Palace grounds in Tokyo. The shrine is considered the sanctuary of Amaterasu-omikami, the legendary sun goddess from whom the imperial line is said to have descended.

There, Akihito read out the "otsugebumi," a document explaining that he would be taking part in a subsequent ceremony to mark his abdication to hand over the Chrysanthemum Throne to his eldest son, Crown Prince Naruhito.

Akihito also read out the document at two other sanctuaries on the Imperial Palace grounds that honor past emperors and other Shinto gods.

Ten other imperial family members, also attired in traditional dress, took part in the ceremonies at the three sanctuaries.