The third son of the Phenex house, one of the respected families in Hell. He was suppose to marry Rias in an arranged marriage between the Gremory and Phenex family but Issei disagreed and challenged him to a battle. Issei got beaten in one hit by one of his Pawns.
Rias then agreed to have a Rating Game with Raiser to settle the matter of the marriage and get revenge for attacking Issei.