Virgin Killer Ninpouchou 

The manga is set in a certain hidden ninja village. Two elite ninja, Goroumaru and Murasaki, compete fiercely to become the village's next village chief. But when Murasaki uses Goroumaru's virginity as a reason to remove him from candidacy, Goroumaru proudly rises to the challenge to lose his virginity. Yet the challenge only plays into the secret plan of the current village chief.