A 35-year-old construction worker was seen in a viral video shoving pickled ginger from a common-use container into his mouth at a Yoshinoya store in Osaka. He thought it would be funny and would gain him even more online followers.

But a court ruled otherwise and on Feb 15 sentenced him to serve two years and four months in prison for his unhygienic prank.

Ryu Shimazu was also fined 200,000 yen (S$1,800), with his sentence also reflecting a drug offence, as investigations showed he was also growing cannabis.

His partner in crime, Toshihide Oka, who recorded the prank and shared the video on social media, was fined 300,000 yen.

Investigations showed that the two men, who both lived in Osaka’s Nishinari ward, went to a Yoshinoya fast food restaurant at around 3am on Sept 29, 2022.

While inside, Shimazu took out his used chopsticks and began eating from a common-use container containing pickled ginger as Oka recorded him with his smartphone.

Yoshinoya Holdings, the company that operates the beef-bowl chain, confirmed the existence of the video on Feb 5, 2023, and filed a damage report with the police.

Shimazu and Oka were arrested in April 2023, and they both admitted to committing the act.

“I wanted to make everybody laugh,” one investigator quoted Shimazu as saying in an Asahi Shimbun report.

Oka reportedly said: “I asked (Shimazu) to do something funny. It was funny as heck, and I wanted everybody to see it. So, I posted it on social media.”

Yoshinoya temporarily shut down the Osaka restaurant and changed all the condiments, including the pickled ginger.

The company said in a statement that Shimazu’s prank “provoked anxiety and ill-feelings among other customers, and raised doubts about safety and security in the food service industry”.

Presiding Judge Satona Takahashi called Shimazu’s actions “selfish and malicious”.

He added that in showing no remorse, Shimazu lacked morals and bore a “heavy” criminal responsibility.

Japan’s major food chains have lately been reeling from an online fad known as “sushi terrorism”, where customers perform disgusting acts inside restaurants in an attempt to add more followers to their social media accounts.

In March 2023, three people were arrested over unhygienic pranks at a conveyor-belt sushi restaurant after footage of their antics sparked outrage online.

The police accused the young trio of seeking to obstruct business at major restaurant chain Kura Sushi, which was bombarded with customer complaints after the video went viral.

The clip shows one member of the group grabbing a piece of sushi from a plate as it passes, shoving the whole morsel into their mouth and then drinking soy sauce directly from a communal bottle.

Similar videos filmed at different restaurant chains surfaced later on platforms including X and TikTok, with some apparently weeks or even years old.

Other unsavoury pranks included customers touching moving pieces of sushi with a freshly licked finger, or sucking the rim of a teacup before placing it back on a shelf.