Takarazuka is a kind of lavish musical theater performed exlusivley by (and in 90% of the time for) women. They put on productions of Western musicals, stories adapted from shōjo manga and Japanese folktales.
It's acted a great influence on the shōjo genre, originaly inspiering works such as "Princess Knight", "Revolutionary Girl Utena" and "The Rose of Versailles" wich is also arguably Takarazuka's best known musical.
The male roles are played by actresses called otoko-yaku, who one Takarazuka instructor described to be "more suave, more affectionate, more courageous, more charming, more handsome and fascinating than a real male."
The otoko-yaku do everything that real men don't do: they tango, say sweet things, show understanding and kindness and never tire of expressing their undying love in the practiced baritones. Shinja Ueda, the president of the Takarazuka, told the Japan Times,
"The performances have an abundance of lines and acting that women want to hear and see from men, however unrealistic...but women are too embarrassed to say."
Explaining the mainly young female fanbase of the productions usualy takes one out of two routes, the one that seems to prevail in the west is that women are drawn to its inherent lesbian overtones. Lesbian themes occur in every Takarazuka performance, simply by virtue of the fact that women play every role.
The second theory is that women find escapism in the actresses performing free and empowered male parts. The subversion of stereotypical gender roles is something that's particurlarly appealing in a society like Japan with notoriously rigid conception of what is male and what is female.
For me personaly I think it's a lot simpler, it's about having something that's just for girls, by girls. Just like with Lolita fashion it's something generally doesn't really involve or appeal to men and it enables you to completley rejecting the notion that it's a man's world for just a moment. I don't really mind all the things I do for and with guys but that's probably due to the fact that I also have my escapism. I like "having my own thing".