Nel
Ile and Nel first appeared in Volume 2 at the Occult Research Club, when Riser is introduces his peerage to Rias after the two of them decide to have a Rating Game. During the Rating Game, they fought against Issei in the replicated gymnasium. Spoiler While they initially gained the upper hand by keeping him on his toes, they both lost to him after being one of the first victims (alongside Mira) to be hit by his Dress Break, before being finally taken out of the fight when Akeno destroyed the building. (Source: High School DxD Wikia)