You're right. The game was never released. I thought it had been out the whole time on Japanese DLSite. At least the game wasn't forgotten. The developer just had bad luck after another it seems.
The highly specific sub-genre of rough succubus on male life draining orgy rape sees good gems from time to time, but not as much love as several more mainstream varieties. I would love to see this finished and I patrol DLSite and my usual forums once every few months for news on it.