Virgin Auction

"Virgin Auctions" do exactly that—instead of selling girls as slaves, girls sell their virginity and the organization behind the auctions receives a fee. Gin, Umi and Yukina have their very personal motives for taking part and are taken care of by Shirohebi and Rongai, a softcore SM couple in charge of newcomers, prior to the auction. Due to Shirohebi's influence, each girl handles her situation differently and eventually takes control of her life.

[From ANN]