Tashirojima, or Cat Island, is a small island off the northern coast of Japan. While the human population stands at only about 100, the cats number in the several hundreds! As of 2014 it was nearly 8 cats for every one person!
Cats were originally brought onto the island because of the residents' dependence on silkworms for silk. Since mice are a natural predator to silkworms, cats helped keep the population of the small rodents down. Fishing was a popular trade on the island and the fisherman grew a fondness for the cats. They interpreting the cats' actions as predictions of the weather and fish patterns. The fisherman, along with the locals, also believed that the cats would bring them good luck. A cat shrine was formed at the center of the island, after a stray rock fell on top of a cat and killed it.
Also, no dogs are allowed on the island! What a cat paradise :)