In this fanfiction, the werewolves could be part of a larger conspiracy. Maybe they are being controlled by a powerful enemy who wants to take over the High School DxD world. Naruto, with his never - give - up attitude, would be the key to uniting the different factions in the school, including the devils, angels, and fallen angels, to fight against this common threat. His ability to see the good in people could also be used to try and reason with some of the werewolves who might be forced into the conspiracy.
Another aspect could be the relationships. Naruto might form a friendship with some of the DxD characters, like Issei. Together, they could face the werewolf challenges. Naruto could teach Issei some of his ninja training techniques to help in battles against the werewolves. And the werewolves might be after a powerful artifact in the school, and Naruto and his new friends have to protect it.