Back when TV Tropes was eliminating pages on works that threatened their precious ad money, I sampled a lot of stuff they deleted, mostly to see what was so horrible about it, and this was one work I found.
The manga is about a brother and sister who fall hard for each other and wind up well.....do I have to spell it out for you?
But seriously, it's a surprisingly good story that treats the subject of incest fairly seriously and does a good job portraying the obvious societal stigma and rejection such an act would bring. Throw in some messed up family dynamics (even more than you'd usually expect for this sort of thing) and a bittersweet and rather realistic ending, and the drama is pretty good.
However, on the flip side of the ledger, it's pretty obvious the author had a thing for the incest sex side of things and was trying to get as much fanservicey mileage out of that as they could, and while it just barely avoids being adult (in the sense lower genitalia aren't shown), the sex scenes are definitely intended, for the most part, for titillation. Throw in the fact the main male character more or less gets raped/taken advantage of by a bunch of girls (related and not) and is an Extreme Doormat for the most part, not only does this send across some messed up signals, it undercuts the seriousness of the work quite a bit, making it appear more like the author was torn between writing pure porn and trying to tell a tragic story and wanted to have it both ways, with the resulting of crippling the impact of either to a degree.
The anime OVA adaptations, for the most part, strip out the drama in favor of the softcore porn, and there can be no doubt what they were intended for, especially since they don't waste a lot of time on anything other than the T&A, so at least they didn't try to serve two masters despite the issues faced in doing so.
Regardless, the story seems forever stalled in time thanks to Japanese law on "obscene materials", so despite the story technically ending on a possible continuation point, it can be considered finished as is, and again, the tragic drama of the manga remains a high point of this work, though the massive amounts of incest fandom pandering tends to cripple it, though if you can live with the mixed message, it's probably worth the read, though I personally had trouble enjoying it due to the Unfortunate Implications.