King Tupou VI of Tonga will receive his traditional installation as monarch at a special kava ceremony on Saturday.
About 200 nobles and their speaking chiefs are expected to take part in the outdoor ritual circle beside the palace in Nuku'alofa.
The ceremony is run by the "sacred hands" undertakers. One of them, Viliami Polovili, says it farewells the late king and heralds the new one.
He says when the new king accepts the first cup of kava, he pledges to do his utmost to serve the country.
The ceremony could take up to three hours.
The ancient ritual will also end the 10 official days of mourning for the late King George Tupou V.
That will allow government businesses and offices to re-open on Monday.
The traditional mourning period will continue.