I'll say, when I first saw this post I thought I wouldn't even consider it as it's not my fetish, but then I thought of how easy it would be to make seeing as the game already has the pregnant belly images one would need. I'll already be learning how to switch the active image for my condom mod anyways.
So, a few questions for you:
Would it be enough, just changing to a pregnant belly once enough semen is inside Hazumi?
How much semen would it take to reach each level of inflation?
What should happen if Hazumi is already pregnant? Should her pregnancy stage go up, or not be changed at all?