Yes, that's not just a double-D in the title, but D times D. That's like, D2. If that's what I think it refers to, I don't know how those poor girls would walk.
Fujimi Shobo's light novel series High School DxD is getting an anime adaptation, though there's no studio currently announced for the project, just the intent to get those girls animated and jiggling. There are eight volumes of the light novel series to work off of, featuring illustrations by Miyama-Zero. A manga adaptation has been running in Monthly Dragon Age since February, drawn by Hiroji Mishima.