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https://www.dlsite.com/maniax/work/=/product_id/RJ01026404.html

Text+SFX -> 001-063
Just SFX -> 064-126
No Text/SFX -> 127-189

Fun, but the order is a bit skewed. It starts with them transformed

Base +7

That is however straight up how the DLSITE archive was arranged.
Not having translated anything, I assumed that the inital mushroom woman was the original monster, she then transforms the guy fucking her and he then fucks and transform the first woman.

Base +7