Japan formally proclaimed Crown Prince Akishino the first in line as heir to the throne on Sunday, the last of a series of ceremonies after his elder brother, Emperor Naruhito, became monarch last year following their father's abdication.
The day-long ceremonies at the palace had been scheduled for April but were postponed because of the coronavirus pandemic and have been scaled back as infection keeps rising, although Japan has escaped the explosive outbreak seen in many other countries.
Under Japanese law, only males can inherit the throne, so Naruhito's only offspring, 18-year-old Princess Aiko, is ineligible. Moves to amend the law lost steam when Akishino's wife bore a son, Hisahito, in 2006.
"I deeply ponder the responsibility of Crown Prince and will discharge my duties," Akishino in orange robe said in front of attendees, most of whom were wearing masks, according to footages by public broadcaster NHK.
Akishino, 54, is one of just three heirs to the throne along with Hisahito, 14, and Prince Hitachi, 84, the younger brother of Emperor Emeritus Akihito, who stepped down last year in Japan's first abdication in two centuries.
Changes to the succession law are anathema to conservatives, but debate over how to ensure a stable succession is likely to intensify.
One option is to allow females, including Aiko and Hisahito's two elder sisters, to retain their imperial status after marriage and inherit or pass the throne to their children, a change that surveys show most ordinary Japanese favour.
Conservatives want to revive junior royal branches stripped of imperial status after the war.