The rising trend for 'animal cafes' in Japan has fuelled a black market illegally trading otters around the country, according to an investigation by World Animal Protection.

Though the trend initially involved cats and dogs, there are now a host of businesses across the country offering encounters with more unusual animals, including rabbits, hedgehogs, snakes, otters, and even owls and penguins. The businesses charge for entry and/or time spent in the cafe, as well as offering a range of drinks and snacks to be enjoyed in the presence of the animals.

Sadly, the animals are often kept in inhospitable conditions. "The otters are sadly heard whimpering, shrieking and making distress calls while customers are interacting with them," World Animal Protection told The Herald.

"Just because a wild animal is cute, it does not mean you should take it home with you," said Cassandra Koenen of Wildlife not Pets.

World Animal Protection is urging people not to support businesses selling or using otters to attract custom, saying these "animals are not pets, they belong in the wild." The Asian small-clawed otter is extremely endangered. The dramatic increase in trafficking rates has concerned experts, who believe it could be the final blow to the species' survival.

Last year a petition to end the practice attracted over 135,000 signatures.