Sushi restaurants in gushing over bizarre videos

For one, there are breaches of etiquette drenching rice in soy sauce, and then there are heinous acts of sushi terrorism when customers at revolving sushi restaurants posted video clips of themselves interfering with food and playing pranks on other customers.

The incidents have caused operators to rethink how they serve their dishes, leading to the plummeting of shares in a leading kaitenzushi chain.

Several acts of what is called sushi terrorism have emerged on Twitter and other social media in recent days, although some seem to date back weeks, and even years.

A clip of the most egregious culinary crime, viewed almost 40 m times on Twitter, shows what appears to be a teenager licking the open top of a communal soy sauce bottle and the entire rim of a teacup, which he then places back on a shelf.

If that wasn't bad enough, the 48 second clip shows him licking his finger and using it to touch two piece of sushi, presumably ordered by another customer, as they travel past on the conveyer belt.

The video, filmed at a branch of the Sushiro chain in the central city of Gifu, caused stocks in the restaurant parent company to plunge nearly 5% on Tuesday.

Other videos show people at other chains putting wasabi on passing pieces of sushi and licking the spoon from a container of green-tea powder that is used by multiple diners.

The videos have provoked an uproar in Japan, where the industry is worth an estimated 740 bn 4.7 bn $5.7 billion. Most of the outrage is reserved for those who don't respect the country's high standards of hygiene.

One Twitter user wrote that this is sickening, with another saying that I can't go to any conveyor belt sushi restaurants. Sushiro, the market leader, said this week that the man who made the viral video had apologised to his parents, but added that it had filed criminal and civil cases.

Sushiro was forced to replace all of the restaurant's soy sauce bottles and rewash its teacups after the clips. It has stopped placing condiments and utensils on each table at the restaurant in question and others nearby, and is asking diners to collect them from a serving point, Japanese media reports say.

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

Some social media users spoke of their nausea after watching the clips, but others expressed sympathy for kaitenzushi operators.

I always wanted to go to Sushiro but I haven't been able to because it's always crowded, the singer Yuya Tegoshi tweeted. The situation is the worst for them now, so I'm definitely going to visit. The firm's president, Kohei Nii, said he had been overwhelmed by the outpouring of support, tweeting: I m so grateful I could cry.