User blog comment:Omega64/Boosted Gear Sub-Species Ideas/@comment-30329599-20161120185817

He can draw power from Women's Breasts. Like he does with Rias but with each Female he gets a different type of Power. Ex. If he gets energy from Akeno's Boobs he might be able to use Holy Lighting, Though like Rias the main downside (For Issei that is) her Oppai will shrink with each use. . . ..