From:
http://pinktentacle.com/2009/11/top-60-japanese-words-phrases-of-2009/60. History girls [reki-jo - 歴女]: Japanese history — particularly that of the Warring States period (mid-15th to early 17th century) — has become a hot topic among many young women in Japan. Called reki-jo (history girls), these newfangled history buffs are reportedly flocking to important historical landmarks and buying up history books, magazines, and samurai-themed knickknacks. Tokyo-based underwear manufacturer Rogin, which sales a line of samurai-themed underwear, has also reported consistently strong sales. About 80% of buyers are women, according to the company.
Researcher Tetsuaki Higashida of the Dentsu Communication Institute suggests history girls may be attracted to samurai for their powerful masculinity — something many women may find lacking in their modern male counterparts. “Gender role reversals have been taking place, with men cooking and women playing golf,” he says. “It’s not unacceptable nowadays for women to take an interest in warlords, which used to be an area of interest reserved for men.”
More on it here>
http://mdn.mainichi.jp/features/archive/news/2009/06/20090613p2a00m0na027000c.html