The James Tiptree, Jr. Literary Award Council announced the winners of the 2009 award. Yoshinaga Fumi
's manga Ooku
was selected along with Greer Gilman's Cloud and Ashes. The members of the jury were not much familiar with manga and Japanese culture but they were deeply impressed by its unique setting that three quarters of men were killed by an epidemic and the the gender roles of men and women were switched.
The James Tiptree, Jr. Award is an annual award given to Sci-fi or fantasy literatures which expand the understanding of gender.
Source: Tiptree Award official website