A members-only Japanese restaurant serving the banned and deadly delicacy "tiger blowfish" liver has been raided, police said Thursday.
Blowfish - also known as pufferfish or balloonfish in the West - derive the name from their ability to expand into a nearly roundish shape as part of a defence to ward off predators.
Japanese gourmands adore the fish for the savoury light taste of its white meat, but parts of the liver and ovaries carry enough toxins to kill not just their natural enemies but human beings as well.
Chefs in Japan who prepare blowfish need a special license but are banned from offering up particularly poisonous parts such as the liver - which some brave epicureans are still willing to eat despite the risk.
In 1975, revered Kabuki actor Mitsugoro Bando died after eating blowfish liver in Kyoto.
The restaurant raided in Osaka belongs to a chain of four outlets, and could not be reached for confirmation as the company's phone numbers are unlisted and the website offers no contact information. New customers must be introduced by an existing member, according to the website.
The raid was conducted Monday, an Osaka prefectural police spokesman said, adding that no health problems have been reported at the restaurant.
But local food safety authorities have indefinitely banned the restaurant chain from serving blowfish, Osaka food safety officials said.
The poisonous substance in the fish, tetrodotoxin, causes dozens to fall ill every year, a few fatally, according to the Japanese Health, Labour and Welfare Ministry.
Police said that the Osaka restaurant served farmed blowfish, which some studies by Japanese marine researchers say does not accumulate poison in the body, but the legal restriction on serving up the potentially poisonous parts remains.