Emperor Akihito canceled his attendance at the rituals and other events scheduled for Wednesday after developing a cough the previous night, the Imperial Household Agency has said.
The agency said the move was a precautionary measure. The rituals are unrelated to a series of ceremonies being held before the 85-year-old Emperor becomes the first Japanese monarch to abdicate in about 200 years.
The Emperor has been taking part in a series of ceremonies ahead of the enthronement of his elder son, Crown Prince Naruhito, on May 1 when the new Imperial era Reiwa, announced by the government Monday, is set to begin.
On Wednesday morning, the Emperor was scheduled to attend a planned ritual but an Imperial household Agency official attended as a proxy.
The Emperor was also scheduled, in the afternoon, to greet volunteers who clean the Imperial Palace. Empress Michiko attended the event alone and conveyed gratitude on the Emperor's behalf, the agency said.
On Tuesday afternoon the Imperial Couple, joined by the Crown Prince and his wife Crown Princess Masako, attended a concert celebrating the Imperial Couple's 60 years of marriage and 30 years of the Emperor's reign.
