Disc image is in MDF format.
The game requires a key, so you need a crack. Drop this exe in the installation folder. I dunno if it's safe but it worked for me.
https://www.mediafire.com/file/v7kju8a046royez/Start.rar/file
Found it here: https://www.anime-sharing.com/forum/hentai-games-38/japanese-%5B100528%5D-%5Bsofthouse-seal-grandee-%5D-%E3%81%9C%E3%81%A3%E3%81%9F%E3%81%84%E9%81%B5%E5%AE%88%E2%98%86%E5%BC%B7%E5%88%B6%E5%AD%90%E4%BD%9C%E3%82%8A%E8%A8%B1%E5%8F%AF%E8%A8%BC-%E3%82%BD%E3%83%95%E3%83%9E%E3%83%83%E3%83%97%E7%89%B9%E5%85%B8-nodvd-95700/#post2286107
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Kazuma2
Jendrej