Japan told its citizens living in China to keep a low profile on Friday, including talking quietly in public, after Beijing blasted Tokyo for releasing treated radioactive water from a wrecked nuclear power plant into the Pacific Ocean.
In messages amplified by reams of state media coverage, Beijing has for months called Japan's decision to release the water selfish and harmful to the environment and human health, even though it has been deemed safe by the UN's nuclear watchdog.
After the release began on Thursday, China announced a blanket ban on all seafood imports from Japan, further complicating relations between the neighbours soured by a range of trade, geopolitical and historical tensions.
"When going out, try to be cautious, such as not speaking Japanese loudly unnecessarily," the embassy said in an alert posted on its website on Friday.
The notice also advised citizens to "pay close attention to the surroundings of the embassy" if planning to visit.
Japan's consulate in Chinese-ruled Hong Kong issued a notice warning of protests there relating to the water release, after 100 marchers took to the streets on Thursday objecting to the discharge.
But long queues at sushi restaurants in Hong Kong backed up the statements of many who said they were not worried about the issue and would continue to visit Japanese restaurants.
{{/usCountry}}But long queues at sushi restaurants in Hong Kong backed up the statements of many who said they were not worried about the issue and would continue to visit Japanese restaurants.
{{/usCountry}}In South Korea, Japan's embassy issued a notice advising its citizens there to "behave cautiously" and avoid "unnecessary trouble" due to a rally planned around the embassy.
South Korean police arrested 16 protesters on Thursday who entered the Japanese embassy in Seoul.