Shibou Yuugi de Meshi wo Kuu.

Summary:

Yuki wakes up to find herself in an unfamiliar manor, wearing a maid uniform and lying on a luxurious bed. Soon, she discovers five more girls, all dressed the same as her. This is the Ghost House, and the only way they can survive is to make it through the traps that lie in wait—deadly games full of blowguns, buzz saws, locked rooms, and weapons. It's a hopeless, terrifying situation for everyone there...well, everyone except Yuki. After all, this is her career at seventeen. Do you think that's odd? She would agree. But that's how some people are—they earn their living playing death games.