Sushi conveyor belt pranks spark outrage in Japan

A handful of unhygienic pranks at sushi conveyor belt restaurants in Japan have sparked stock slumps, venue overhauls and legal action, along with furious social media commentary.

Several videos dubbed "sushi terrorism" have emerged on social media including Twitter and TikTok in recent days, some of them apparently weeks or even years old.

In one, viewed nearly 40 million times on Twitter, an apparently teenaged customer licks the top of a communal soy sauce bottle and the rim of a teacup he then places back on a shelf, before licking his finger and touching a piece of sushi as it goes past on the belt.

The video, filmed at a branch of the Sushiro chain in the central Japanese city of Gifu, prompted stocks in the restaurant's parent company to plunge nearly five percent Tuesday.

Other videos emerged showing customers at different chains putting wasabi on passing pieces of sushi or licking the spoon in a communal green tea powder container.

Though the incidents appear to be confined to just a few videos, they have caused an uproar in Japan, a country with famously high standards of cleanliness.

"This is sickening," one Japanese Twitter user wrote in response, with another adding "I can't go to conveyor belt sushi restaurants anymore."

In a statement, Sushiro said the teen behind the viral video had apologised, along with his parents, but that the firm had filed a formal police complaint.

"As a company, we will continue to respond firmly with both criminal and civil cases," it said.

It said all the soy sauce bottles at the affected store had been replaced and all the cups cleaned and announced new restaurant policies.

At the Gifu branch and others nearby, customers will now take utensils and condiments to their tables from a serving point, and nationwide, diners will be able to request disinfected tableware.

Two other affected chains, Hama-sushi and Kura Sushi have both also reportedly said they plan to take legal action, with the latter now planning to install cameras above conveyor belts to monitor customers, Jiji press agency reported.

After the initial outcry, there was something of a wave of support for the affected companies, with some tweeting their backing under the hashtag #saveSushiro.

"I've always wanted to go to Sushiro but haven't been able to because it's always crowded," Japanese singer Yuya Tegoshi tweeted.

"But the situation now is the absolute worst for them, so I'm definitely going to visit."

Sushiro president Kohei Nii said on Twitter he had been overwhelmed by "an outpouring of support."

"I'm so grateful I could cry."