User blog comment:B214/Talk About What You Want! 2/@comment-24098614-20140705201552/@comment-1359322-20140706014339

In Volume 18 said, Issei lost some of his pervertedness that was regained due to Azazel who hand down the dream of seeing Gabriel naked. So i guess seeing girls naked too many times has also make Issei develop some immunity to it. Issei needs new and fresh breasts and i don't think Kuroka can provide those, Issei seen and taste her too many times already. Same with Rias and the other girls. They need to prepare to cry soon.