Sword of the Stallion, Vol. 1 (light novel)

An honorable knight fallen from grace…returns as a total stud! Ras Talion was once a respectable knight who single‑handedly slayed a Greater Dragon, but he lost his beloved in that same battle. Now Ras is a mercenary and a hedonist who visits brothels night after night. He's even known throughout the empire by the derisive nickname "the Stallion." One day, he comes face‑to‑face with the impossible—the supposedly deceased imperial princess Fiarca, his ex‑fiancée. Alive and kicking, she assigns him a mission she believes only he can accomplish. To save the empire from impending doom, he must seduce a princess of the neighboring kingdom!