Queen's Blade (クイーンズブレイド Kuīnzu Bureido) is a series of visual combat books published by Hobby Japan, based on the licensed works from Lost Worlds. First published in 2005, it features only female characters.
Beginning with the 7th series, it uses all-new game rules compatible with the Lost Worlds books.
Anime: In 4 years time the competition that will decide who the next Queen shall be will start. The strongest warrior will continue to rule the country according to tradition and expand it. The contestants need only be older than 12 years. They need not be human, intelligent or even of that country. The rules for the tournament are simple: murder is allowed. Any weapon can be chosen. The winner is decided when one of the participants flees or can't move anymore. Such event is broadcasted trough a crystal sphere by the court's magic teacher to all population to see and enjoy.
(source: Wikipedia, ANN)