Throughout this year, a series of elaborate ceremonies are being held in Japan to mark the enthronement of Emperor Naruhito and the beginning of the new imperial era, named Reiwa, said to mean ¡°beautiful harmony.¡±

The Daijosai, the most secretive and arguably controversial part of those ceremonies, was set to begin Thursday evening and continue into the early hours of Friday. The ceremony is a Shinto rite during which a new emperor prays for peace and a rich harvest for the nation.

The ceremony, which originated centuries ago, is mysterious because the exclusive ritual is attended only by the emperor and a handful of female assistants, all wearing traditional-style dress, and according to Shinto beliefs involves deities descending to the ground during the ceremony.