Yasuhiko Nishimura, a former top police bureaucrat, was promoted to head of the Imperial Household Agency on Tuesday after serving in the No. 2 post.
Nishimura, 64, has replaced Shinichiro Yamamoto, 69, as grand steward following a series of ceremonies and rites relating to Emperor Naruhito's ascension to the chrysanthemum throne that finished in early December.
Nishimura, who has also served in other key posts such as deputy chief Cabinet secretary for crisis management, will handle events including a ceremony in April that will formalize the position of Emperor Naruhito's brother, Crown Prince Akishino, as first in line to the throne.
Nishimura joined the National Police Agency after graduating from the University of Tokyo. He was also chief of the Tokyo Metropolitan Police Department. He became vice-grand steward of the imperial household in September 2016.
Kenji Ikeda, 58, a former senior bureaucrat at the Ministry of Internal Affairs and Communications, will take over Nishimura's previous role.