Queen's Blade is a series of combat books that started back in 2005, based on the '83 Lost Worlds books. Unlike the original black and white LW books, the QB books contain full-colour illustrations of beautiful women in sexy poses, drawn by famous japanese artists, so it's no wonder it became very famous there, spawning mangas, anime adaptations and 2 PSP games.
Regarding gameplay, Lost Worlds/Queen's Blade is a diceless gladiatorial system, where you and your opponent select a maneuver each turn and a complex matrix in each page determines both of your outcomes (for example, if you do a swing and your opponent dodges, most of the time you'll see your swing suceeding and the opponent getting hurt). The "How to play" page has more detailed info on the game.
Besides the "classic" Queen's Blade series of books, there's also Queen's Gate, a spinoff with popular characters from other franchises like Mai Shiranui or Dead or Alive's Kasumi, Queen's Blade Rebellion, the on-going continuation of QB's story with new characters and situations, and Queen's Blade Grimoire, the next series with characters based on fairytales.
Next Queen's Blade Grimoire books:
N/A
Next Queen's Gate books?:Painkiller Kotone-chan (Hyper Nurse series): TBA
Sen Tokugawa (Samurai Girls): TBA
