Part 1 of the haigure gallery uploaded by EroSeninJiraiya (which you can find a link to below). I know judging by the file names, it seems like there are several missing images, though this is the complete set (with the exception of two virtually blank .bmps) from the only available upload of it I was able to find. If more actually does exist and you know where to find it, I'd appreciate it if you could point me in the right direction so I can update the gallery.

Links:
Part 2: http://g.e-hentai/g/467657/6b7b6996af/
Direct Download (including the game): http://viid.me/9Mwbq

For the direct download, enter "ハイグレ" (without quotations; copy-pasta works fine) into the field at the top of the page marked キーワード, and click the button underneath or press enter. Then click the appropriate link (it'll include English instructions) on the page that brings you to. Sorry if that seems obvious, just idiot-proofing.