All three of them have unbalanced personalities, each in a different way. The interactions between these personalities could be interesting in itself. However, the recurrent twincest innuendo keeps screaming "contrived, contrived!", drowning out the plot. I never thought that I would actually see that kind of innuendo in broadcast-level material. It is rather disturbing. Some topics are simply not possible to handle well, I believe. And in any case, this anime is not doing it.
The graphics are good, the landscapes are better than most I have seen in anime, even the weather. The plot, while openly contrived, is new and interesting. This anime could have been so good.