Yoshiwara (吉原市 Yoshiwara-shi) was a city located in eastern Shizuoka Prefecture. On November 1, 1966, Yoshiwara was merged with the city of Fuji. During the Edo Period, Yoshiwara was a post town known as Yoshiwara-juku on the Tōkaidō (road). At the time of its merger, the town had an estimated population of 90,224 and a density of 516.86 persons per km². The total area was 174.56 km². The town was served by both the Tōkaidō Main Line and the Gakunan Railway.