However, this is a terrible product to test market demand for their games. That Illusion has finally taken an interest in the English market is great news. This is basically a demographic paradox: their primary audience won't have the hardware to play their game, and the few who DO have the hardware are unlikely to be interested. In a Venn diagram, the overlap between eroge fans and early VR adopters is probably minimal eroge fans tend to have less capable hardware than your typical gamer since the majority of eroge have very low system requirements. I doubt this title will do well in either Japan or overseas, at least while VR adoption is low. And only a very small subset of those would even be interested in a hentai game, much less one of Illusion's simple sex sims.
Only extreme early adopters would be willing to pay the $600 or so for the headsets, much less the extra $300 or more for the necessary GPU/hardware upgrade. The VR-only platform requirement is going to extremely limit their audience for this particular title.
The English is poor-they can't seem to construct actual sentences expressing a coherent thought-but it's not machine-translated at least.
It looks like only the demo is being released on Steam. The English official site is instructive.