Shishaku Valmont - Kiken Na Kankei

The plot focuses on the Marquise de Merteuil and the Vicomte de Valmont, rivals who use sex as a weapon of humiliation and degradation, all the while enjoying their cruel games. Their targets are the virtuous Madame de Tourvel and Cécile de Volanges, a young girl who has fallen in love with her music tutor, the Chevalier Danceny. In order to gain their trust, Merteuil and Valmont pretend to help the secret lovers so they can use them later in their own treacherous schemes.
Note: The manga is an adaptation of "Les Liaisons dangereuses" by Pierre Choderlos de Laclos.