An interview with the Senran Kagura 2 developers has shed some additional light on their handling of assets in their physics engine.

Speaking to Siliconera, producer Kenichirō Takaki indicated that there is an upper limit to what their current engine can handle in terms of the character's bust size before body parts start clipping through each other. However, the engine is built to handle larger assets first making smaller characters require special attention during development.

Takaki's quote on he topic: "Hmm, I think that characters like Ryoubi or Mirai are the hardest to deal with because they have small breasts. Since the whole game is based on larger breast sizes, and that’s what the [physics engine] is built around, we actually have to customize the movement on [small breasted characters] to make it work."