Moreover, the issue of divinity was clouded this summer when Nobuo Ishihara, deputy secretary of the Cabinet of Prime Minister Toshiki Kaifu, was asked if the Emperor did indeed become a god.

Instead of denying it, Mr. Ishihara said, ''Many scholars have theories, but the Government is not in a position to comment.'' Government officials said later that he was only trying not to offend true believers in Japan, but the effect of the statement was to leave the issue open.

The daijosai is to take place during the night, with 1,000 guests waiting outside. The Government argues that the rites do not violate the Constitution's ban on Government support of religion because the ceremony is basically a secular harvest ritual with ''religious elements'' in it.

Socialists Plan Boycott

Objecting to the religious nature of the ceremony, the Socialist Party has announced that it will boycott the daijosai. Radical leftists have firebomed several Shinto shrines, while rightists fired shots into the home of a university president who criticized the Government for its sponsorship.

Details of what actually happens during the enthronement ceremony are kept secret, so there has been an abundance of speculation.

According to the Imperial Household Agency, the ceremony features the Emperor, wearing flowing layers of robes and accompanied by six ritualists, entering a specially built shrine late at night and then going into an inner sanctum accompanied only by two female priests. In the inner chamber is a bed.

Everyone agrees that the core of what happens next is an act of thanksgiving and prayer as the Emperor offers the first rice of the season to his ancestor and to the deities of heaven and earth, then partakes of it himself.