Oiran was a courtesan at Yoshiwara in Edo era.Yoshiwara has been a red light district since the 17 th century andit is still keeping the second oldest trade running. However this parade is for the purpose of valuing the art and culture sides of this business in the old days and nothing to do with brothel industry promotion. Anyway, this site is being managed by tourism bureau of Tokyo Municipality.
http://www.gotokyo.org/jp/kanko/taito/event/ichiyouoiran.html
