九十九里浜
Although the Chinese unit was unofficially used in Japan since the Zhou Dynasty, the countries officially adopted the measurement used by the Tang Dynasty (618–907 AD). The "ri" of an earlier era in Japan was thus true to Chinese length, corresponding to six chō ( 500–600 m), but later evolved to denote the distance that a person carrying a load would aim to cover on mountain roads in one hour. Thus, there had been various "ri" of 36, 40, and 48 chō. In the Edo period, the Tokugawa shogunate defined 1 "ri" as 36 chō, allowing other variants, and the Japanese government adopted this last definition in 1891. The Japanese "ri" was, at that time, fixed to the metric system, ≈ 3.93 kilometres or about 2.44 miles. Therefore, one must be careful about the correspondence between chō and "ri". See Kujūkuri Beach (99-"ri" beach) for a case.