Awww, dammit. You bit me with the GM bug. I'll be willing to run this for you and maybe a couple other people.
Let me lay out how I'd run it first, to see if you're interested.
First, the labyrinth, and the creatures within, would not be trying to kill you. Sure, some monsters or traps might attack the character so they can do evil things to her, but they won't kill her. That's not the Labyrinth goal. It wants you to decide to stay, or make you so weak that you can never leave. It try to wear you down, applying penalties and bad status effects, while the character gets better armor and magic and experience to counter these. If you can keep going long enough to get the scroll, then you win. If the penalties get so bad that you can no longer search, you loose.
I'm also not going to stack the odds against you. I'll set you against things that a ninja could conceivably beat. So if the character is smart, skilled, and lucky, sexy things might not happen.
The labyrinth wants you to stay and make more traps, monsters and puzzles to entrap other poor girls. There will be small elements of pregnancy, and other insane ninja who have failed will be around to play with the character. IF you have any other requests, I'd be happy to work them in.
The system will probably be dice chucker. (http://www.1km1kt.net/rpg/Dice_Chucker.php
Would that appeal?
Edit: Goddamn spelling!