Arslan Senki: Fuujin Ranbu

After managing to get past the battles concerning the royal successor for Sindhura, Arslan and company made their triumphal return to Pars to find Hilmes the brave general with the silver mask standing in their way. And by the time they somehow get Hilmes to stand down and they can be on their way to thee capital once again, an even larger threat was fast approaching the land of Pars.
(Source: Anime News Network)