Niplheim's Hunter: Branded Azel

While fighting with a demon, Azel is captured and fucked silly. After managing to escape she notices that a Crest engraved by the demon is left on her abdomen, a crest that causes insatiable sexual desire...

Kakouya is tormenting the daughter of a blacksmith, a girl named Rita. In her sex-induced daze, she sells the Dragon Fang to Azel. When equipped, it grants her the powerful Dragoon Armor, which allows her to defeat the Demon Lord Lasbos! But as he dies, he tells Azel that the seal on her body can't be removed.