>>123597
Yeah, it's about how this guy packages his games, looks a bit complicated but you'll have no problems once you figured out. Usualy there are X parts part 1 2 and so on. Open part one with your archive program, I use WinRAR, but the built-in should work too, so just click on it. Extract files and you will see a rar archive named with the dlsite code RJXXXX. inside this archive is the game. Extract it, rename it and put it into your games folder. Some games, have files with japanese names, for those use BandiZIP or set your locale to jp and use any program to unpack. Also, for older games, there could be an iso file instead of the game files. That is an old CD-ROM image of the game. Mount it with Acohool, PowerISO and install the game, alternative method, just unpack it with WinRAR
https://www.win-rar.com/start.html?&L=0
Gave you all this info to keep, it's common knowledge for playing pirate games. In your case it's easy, click on part1 it will autmatically extract part 2 then extract from the RJXXX archive you get.