Seirei Gensouki: Spirit Chronicles Volume 13 by Yuri Kitayama

Agreeing to escort Princess Christina to the Kingdom of Galarc was one thing... but facing the overwhelming strength of Beltrum's army could've been more than our heroes group bargained for. And yet, thanks to Rio's otherworldly strength, Charles and his army were dealt with swiftly, with the former now captive as Rio's prisoner.

But upon their arrival in Galarc, Rio has another challenge to overcome... The hero, Sakata, is waiting for him!