[...]
The new emperor's clothes
For his enthronement, the new emperor will wear an outfit in the sokutai or ceremonial style. The outfit is now rarely seen and is dominated by a voluminous draped brown-gold outer robe with long, wide sleeves and a cinched waist.
Only the emperor wears this color [...]
Royal attire often includes motifs of birds, as they were considered divine envoys in ancient times and the emperor's outer garment is decorated with a mythological Chinese phoenix, believed to symbolize the arrival of peace.
During the ceremony, the emperor and other male royals will carry a shaku or scepter -- a narrow plain wooden plate not unlike a large shoehorn.
[...]
But the crowning glory of the emperor's outfit is the kanmuri hat, which consists of a simple flat black base and a towering black tail at the back that extends upright 60 centimeters.
Fit for an empress
Incoming Empress Masako will wear an elaborate outfit commonly known as junihitoe or many-layered robe.
[...]
There is no set rule on the number of layers, though outgoing Empress Michiko wore nine robes during her husband's enthronement.
Masako is likely to choose her own colors but similar motifs to those donned by Michiko in 1989. [correction: Emperor Akihito's enthronement was in 1990]
[...]
Masako's hair will be sculpted into a style that sweeps up and out to the sides with a long ponytail extending from the back and a large golden hairpiece pinned above her forehead.
[...]
The sacred treasures
[...]
The treasures are the Yata no Kagami, a mirror, Kusanagi no Tsurugi, a sword, and the Yasakani no Magatama, an unspecified jewel.
[...]
"We do not know exactly what they are like," said Eiichi Miyashiro, a senior journalist at the Asahi Shimbun newspaper and royal expert.
The treasures will be passed over in a ceremony held on May 1, which the new emperor attends in Western-style clothes and is off-limits for female royals.
During the ceremony, a replica sword and the original jewel will be handed over, wrapped in cloth. Both are kept at the palace, along with a replica mirror not used in the ceremony.