An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters. Also it could mean that due to deforestation there may be a lack of food and/or water. The International Union for Conservation of Nature (IUCN) has calculated the percentage of endangered species as 40 percent of all organisms based on the sample of species that have been evaluated through 2006. (Note: the IUCN groups all threatened species for their summary purposes.) Many nations have laws offering protection to conservation reliant species: for example, forbidding hunting, restricting land development or creating preserves. Only a few of the many species at risk of extinction actually make it to the lists and obtain legal protection. Many more species become extinct, or potentially will become extinct, without gaining public notice.

The Red-crowned Crane (Grus japonensis), also called the Japanese Crane or Manchurian Crane, is a large crane and is the second rarest crane in the world. (Chinese: 丹顶鹤; Chinese: 丹頂鶴; Hanyu Pinyin: Dāndǐng Hè; Japanese: 丹頂 or タンチョウ, tancho; the Chinese character '丹' means 'red', '頂/顶' means 'crown' and '鶴/鹤' means 'crane'). In East Asia, it is known as a symbol of luck, longevity and fidelity. At 140 cm (55 inches) high, the crane does not make easy prey, for all that it stands out in its natural habitat of marshes and swamps. When it matures, the Red-crowned Crane is snow white with a patch of red skin on its head. This patch of skin becomes bright red when the crane becomes angry or excited. This species is the heaviest crane, typically 7.7–10 kg (17-22 lb), although large Sarus Cranes are taller. The maximum weight a male Red-crowned Crane is known to attain would be 15 kg (33 lbs.)

In the spring and summer, the Red-crowned Crane breeds in Siberia and occasionally in northeastern Mongolia (i.e., Mongol Daguur Strictly Protected Area). Normally the crane lays 2 eggs, with only one surviving. Later, in the fall, it migrates in flocks to Korea, Japan, China, Taiwan, and other countries in East Asia to spend the winter. All Red-crowned Cranes migrate, except for a flock that is resident in Hokkaidō.

Hokkaidō (北海道^?, literally "North Sea Circuit"), formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island and the largest, northernmost of its 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaidō from Honshū, although the two islands are connected by the underwater Seikan Tunnel. The largest city on Hokkaidō is its capital, Sapporo, which is also its only ordinance-designated city.

The conservation status of a species is an indicator of the likelihood of that species remaining extant either in the present day or the near future. Many factors are taken into account when assessing the conservation status of a species: not simply the number remaining, but the overall increase or decrease in the population over time, breeding success rates, known threats, and so on.

Japan (日本, Nihon or Nippon^?, officially 日本国 Nippon-koku or Nihon-koku) is an island country 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. The characters which make up Japan's name mean "sun-origin", which is why Japan is sometimes identified as the "Land of the Rising Sun".

Japan is an archipelago of 6,852 islands. The four largest islands are Honshū, Hokkaidō, Kyūshū and Shikoku, together accounting for 97% of Japan's land area. Most of the islands are mountainous, many volcanic; for example, Japan’s highest peak, Mount Fuji, is a volcano. Japan has the world's tenth-largest population, with about 128 million people. The Greater Tokyo Area, which includes the de facto capital city of Tokyo and several surrounding prefectures, is the largest metropolitan area in the world, with over 30 million residents.

The IUCN Red List of Threatened Species (also known as the IUCN Red List or Red Data List), founded in 1948, is the world's most comprehensive inventory of the global conservation status of plant and animal species. The International Union for the Conservation of Nature and Natural Resources (IUCN) is the world's main authority on the conservation status of species. A series of Regional Red Lists are produced by countries or organizations, which assess the risk of extinction to species within a political management unit.

The IUCN Red List is set upon precise criteria to evaluate the extinction risk of thousands of species and subspecies. These criteria are relevant to all species and all regions of the world. The aim is to convey the urgency of conservation issues to the public and policy makers, as well as help the international community to try to reduce species extinction.

Major species assessors include BirdLife International, the Institute of Zoology (the research division of the Zoological Society of London), the World Conservation Monitoring Centre, and many Specialist Groups within the IUCN's Species Survival Commission (SSC). Collectively, assessments by these organizations and groups account for nearly half the species on the Red List.