, or sometimes just , is an island located roughly 1.5 kilometers northeast of the city of Niihama

Niihama, Ehime

is a city located in the eastern part of Ehime, Japan. It has the third largest population in Ehime, behind the prefectural capital of Matsuyama and the recently expanded city of Imabari.Niihama was founded on November 3, 1937...

 (which it is officially a part of) in Ehime Prefecture

Ehime Prefecture

is a prefecture in northwestern Shikoku, Japan. The capital is Matsuyama.-History:Until the Meiji Restoration, Ehime prefecture was known as Iyo Province...

, Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

. It has a circumference of approximately 8 kilometers and an estimated population

Population

A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...

 of 400. The primary occupations on the island include raising shrimp

Shrimp

Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

 for consumption, and growing mikan

Mikan

The satsuma is a seedless and easy-peeling citrus mutant of Japanese origin introduced to the West.In Japan, it is known as mikan or formally unshu mikan . In China, it is known as Wenzhou migan . The Japanese name is a result of the local reading of the same characters used in the Chinese...

 and a distinctive type of white potato

Potato

The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...

.

Due to its rapidly aging population and its geographic isolation from Niihama and the main island of Shikoku

Shikoku

is the smallest and least populous of the four main islands of Japan, located south of Honshū and east of the island of Kyūshū. Its ancient names include Iyo-no-futana-shima , Iyo-shima , and Futana-shima...

, Nii Ōshima faces serious problems of depopulation. There is a ferry that runs between Nii Ōshima and Niihama approximately once every hour, taking fifteen minutes to complete a one-way journey. At one point there was the possibility that a bridge might be built to connect Ōshima and Shikoku, but these plans are now considered to be unlikely to be executed.

On the southern side of the island sit the remains of Ōshima Castle. This, along with the presence of two Shintō shrines

Jinja (Shinto)

A Shinto shrine is a structure whose main purpose is to house one or more Shinto kami....

on this small island hint at Ōshima's former importance as a regional center of trade and commerce.