Sinking into the steamy hot springs, the giant rodents of the Izu Shaboten Koenclose their eyes as people gather around to take pictures.The noise of cameras and the crowd do not stop the animals from falling asleep in the water.The creatures are capybaras, the largest rodent in the world.The five capybaras might not realize they are the main attraction at Izu Shaboten Koen.The zoo is just two hours south of Tokyo by train.Its grounds are home to over 100 different animals and birds, as well as cactus plants from around the world.Workers expect the zoo will make money from all the people interested in seeing the capybaras this year.It helps that 2020 is the Year of the Rat on the Chinese Zodiac.Capybaras are a close relative of rats.Masahiro Takeda is a zookeeper at the Izu Shaboten Koen.He says the capybaras are the highlight of the zoo, so the Year of the Rat is a chance to "push their popularity up even more.""We're really hoping that this will catch on with people from all over the world visiting Japan, too," he told the Reuters news agency.Capybaras are not native to Japan.They come from the tropical forests of South America.The animals live close to bodies of water, are great swimmers and can stay underwater for up to five minutes.As adults, they can weigh anywhere between 35 and 65 kilograms.In the wild, capybaras usually live in groups of around 10 to 20.They are known for being calm and friendly with other animals.That is probably why so many creatures like to be with or even sit on them.The Izu Shaboten Koen's winter tradition of giving the capybaras baths every day started almost 40 years ago.One day, a worker was cleaning their enclosure with hot water when he turned around and noticed something:The animals had crowded together and were trying to sit in a warm puddle.The baths quickly became popular at Izu Shaboten Koen and other zoos across Japan,where the number of capybaras jumped from 126 in 2006 to 422 in 2016.The popularity of the large rodents in Japan has led to sales of a soft toy and other products called ‘Kapibarasan.'And online videos of bathing capybaras have been played hundreds of thousands of times.At Izu Shaboten Koen, the capybaras eat apples and leaves thrown by their keeper into the hot bath water before they fall asleep.When the capybaras are awake, visitors can wear special mittens to touch and feed the animals.People who stop for food at the zoo's restaurant can order something special: A beef burger with bread in the shape of a capybara.Its eyes and mouth are made of chocolate.Takeda estimated the zoo has had 20 to 30 percent more winter visitors since it started publicizing the bathing capybaras."I'd only ever seen the capybaras sit in hot springs on TV, so I really wanted to see it in person,"said Kayo Kogai, who was a recent visitor to the zoo."They look so relaxed ... I would really like to join them in their bath," Kogai's friend Mizuki Aoki added with a laugh.