User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-67.176.158.104-20140702175236

Issei used his new penetrate ability to see through Gabriel's clothes. Wonder if he is going to use it on other people as well. Like Xenovia's sword master. The woman that's a part of Gabriel's brave saints.

And maybe he could secretly use it on the girls at his school from now on too. No longer needing to get close enough to peep on them like the other members of the perverted trio. He could just see through the buildings and see them getting changed.