User blog comment:B214/Question and Answers/@comment-82.178.40.107-20140127122853/@comment-16281343-20140128000053

Again, that's pre-Volume 5.

Anyways, Issei hasn't attended a social gathering in the Underworld, except in the party for the Young Devils. So, we don't know how Issei will fair in that situation, we don't know whether his perverseness will let loose or not. :)