Ookami no Kuchi - Wolfsmund Manga
Wolfsmund is a dark historical manga set in the early 14th century of Europe (Switzerland). The story revolves around the eponymous fortress in the St. Gotthard Pass which is ruled by a sadistic tyrant. Basically, each chapter deals with characters who for some reason have to cross the pass and who end up getting interrogated by the mentioned tyrant.
What sets this manga apart is the fact that there's rarely a happy ending for our protagonists. The author pulls no punches to show us just how brutal and inhuman the Middle Ages really were.