The Forgotten Hero (Highschool DxD x Male Reader)

Everyone knows of the Great War, three factions 'Angels' 'Devils' and 'Fallen Angels' fought among each other until the four Devil Kings were killed, but what they don't know is that there was in fact a fourth faction...(Y/n) has just transferred to Kuoh Academy but he holds a great secret, he is the last descendant of the (L/N) family. A strong powerful family whom had fought in the Great War but they were Human....no, they were Heroes.
I Do Not Own Highschool DxD