Its Not Over Yet! (Oc x Highschool DxD)

Muichiro "The Guardian" Gremory is a devil of the gremory family and a member of rias' peerage at a young age he managed to unlock a power that was completely different to the Gremory's Power Of Destruction and at that young age he Gained the Cannon Destroyer and armor the freiturner and the ability to weild it and the gremory tried to keep it a secret for years what would happen if that secret that he holds a power unlike any other gets leaked? Find Out!