Yuto Kiba is a student of Kuoh Private Academy who know for his attracted looks around all female students. He's truly a reincarnated Devil and the night of Team Gremory who bears Two Sacred Gears.
He was once a test subject in project Holy Sword in which they were trying to train kids to wield the strong Holy Sword Excalibur. Though in the end no one could wield it and the test subjects were to be disposed of. The other subjects sacrificed themselves to allow Kiba to escape for he bears the Longinus Sacred Gear Sword Birth which he can create sword switch special powers at will. Though he nearly died but Rias Gremory found him and reincarnated him as her knight.