Security is tight at every G7 summit, but this year's host Japan has more to prove than most, after an attack last month on the prime minister and the 2022 assassination of ex-premier Shinzo Abe.
Some 24,000 security personnel are reportedly being deployed to Hiroshima during the summit, most dispatched from other parts of the country.
Well ahead of the May 19-21 talks, patrolling police have been weaving between tour groups in the western city's famed Peace Park.
Security personnel were also motoring up and down the river that runs alongside sites like the Atomic Bomb Dome, with helicopters regularly buzzing overhead.
The measures have extended far beyond the city, including to the capital Tokyo, where messages on the train system warn of heightened security for the summit.
Major cities in Japan do not generally have rubbish bins in public places, but security personnel have been sealing off other places considered to pose a potential threat.
Vending machines on subway platforms have also been unplugged and sealed with tape, along with apologetic signs warning they will be unavailable during the summit for security reasons.
In Hiroshima, signs across the city and in hotels remind locals and tourists alike that the summit will cause disruption, including the closure of streets and access to the island of Miyajima, which leaders are expected to visit.
Dozens of schools and other institutions have simply opted to close during the summit, according to local media.
The measures are likely to be closely scrutinised less than a year after a gunman assassinated former prime minister Abe as he campaigned in the city of Nara.
Then in April, a man hurled an explosive device towards Prime Minister Fumio Kishida shortly before he was due to deliver a campaign speech in the city of Wakayama.
He escaped unharmed, but the fact that an assailant was able to throw the device at such close range so soon after the Abe murder prompted renewed criticism of security arrangements in Japan.
The head of Japan's National Police Agency, and the local police chief, resigned in the wake of Abe's assassination after an investigation confirmed "shortcomings" in the security for the former leader.
Kishida has instructed police to step up security around the G7 "so that guests can visit Japan with peace of mind".
Leaders from G7 members Japan, the United States, Canada, Britain, France, Germany, Italy and the European Union will be joined by invitees including Brazilian President Luiz Inacio Lula da Silva and Indian Prime Minister Narendra Modi.
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© Agence France-Presse
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