Recently I discovered that the latest Senran Kagura game for the 3DS, Senran Kagura 2: Deep Crimson, has a bit of DLC with substantial BE involved.
It's the third DLC Pack, titled "Burst".
In the DLC, Mirai (in the gothic black), the least busty of the main cast, seems to have obtained a special milk that can increase breast size. From the looks of it, the BE can happen with more than just her:
Unfortunately I don't have a Japanese 3DS so I can't confirm how extensive the BE content is, but if anyone does, here's a lead!