Japan's royal family is now on Instagram -- but don't expect any candid selfies from its official account, which went live Monday in a cautious social media debut for the ancient monarchy.

The first 19 posts are formally staged photos and videos of Emperor Naruhito and Empress Masako carrying out royal duties at recent public appearances.

Nonetheless, more than 160,000 users have followed the Imperial Household Agency (IHA) account, which was announced a week ago but set to private until Monday.

The Japanese monarchy has mythological origins stretching back more than two millennia, and any public criticism of the emperor remains taboo in the country.

By joining social media, the institution hopes to spark interest among younger generations about what the imperial family does, an IHA spokesperson confirmed to AFP.

But, perhaps predictably, the posts under the Instagram handle kunaicho_jp contain no behind-the-scenes juice.

Strictly factual captions explain what the emperor did on what day, from meeting foreign dignitaries to admiring bonsai trees, with comments moderated.

The account does not follow any other users, and has so far not ventured into Instagram Stories.

"The IHA is on Instagram! I thought it was an April Fools' prank!" one X user wrote in reaction to the launch.

"When I heard the IHA created an Instagram account, I quickly checked it out. But of course the emperor wouldn't post 'today's lunch (heart emoji)' or anything like that," wrote another.

Some users joked it was good the royals had chosen the more "civilised" Instagram over X, formerly Twitter.

Naruhito ascended the Chrysanthemum throne in 2019 in a tradition-laden ceremony after his highly popular father became the first emperor to abdicate in over two centuries.

Other monarchies have created social media accounts, including Britain's royals, who have recently been at the centre of a storm of rumours and conspiracy theories.

The manipulation of a family photograph the palace released to the media fuelled online speculation over the whereabouts of Catherine, Princess of Wales, who later revealed she had been diagnosed with cancer.