Big Breasts Fantasy(2012)

During the feudal era war develops on several kingdoms and territories, and Ryuuto leads one of the sides until one day his political enemies decide to set up a trap and send him to hunt a demon – which turns out to be a succubus known for killing several men already. The succubus falls in love with him – or at least with his lower part and energy – and decides to help him succeed in his military quest.