Tashirojima is a small island in Ishinomaki, Miyagi, Japan. It lies in the Pacific Ocean off the Oshika Peninsula, to the west of Ajishima. It is an inhabited island, although the population is quite small (around 100 people). It has become known as "Cat Island" due to the large stray cat population that thrives as a result of the local belief that feeding cats will bring wealth and good fortune. The cat population is now larger than the human population on the island. There are no pet dogs on the island due to the large cat population.
The island is divided into two villages/ports: Oodomari and Nitoda. Ajishima, a neighbouring island, used to belong to the town of Oshika, while Tashirojima was a part of the city of Ishinomaki. On April 1, 2005, Oshika merged with Ishinomaki, so now both islands are a part of Ishinomaki.
Since 83% of the population is classified as elderly, the island's villages have been designated as a "terminal village" which means that with 50% or more of the population being over 65 years of age, the survival of the villages is threatened. The majority of the people who live on the island are involved either in fishing or hospitality.
The island is also known as Manga Island, as Shotaro Ishinomori built manga-related buildings on the island, resembling a cat.
In Japan's late Edo Period, much of the island raised silk-worms for their textiles. The residents kept cats to chase the mice away from their precious silk-worms. As of today, the feral cat population outnumbers humans 6 to 1 on this small Japanese Island.
However, the residents and thousands of tourists who flock to Tashirojima every year do not mind being outnumbered by their feline friends. In Japanese culture, the cat is considered a good luck charm, said to bring money and good fortune to all who cross their path.
Explanation from: https://en.wikipedia.org/wiki/Tashirojima