User blog comment:Gemini Sunfall/Main Story and Sidequest Translation is Done, Now What?/@comment-40266882-20190724162832/@comment-36674939-20190724215200

You only need to purchase Part 2, as it contains all of the game data from the first part--with the exception of H-scenes,  "Merging" with Part 1 is really just a matter of taking the scenes from Part 1's pictures folder and dropping them into Part 2's.