What stays with me the longest about this vn is the questions it raises concerning madness and morality in general. From Fuminori's perspective, he's literally eating (and killing) monsters. Saya herself apparently arrived on Earth as mostly a blank slate, too. It's shown that she's quite superior in ability to humans when it comes to learning, and she's not unsympathetic to people who don't see her as an Eldritch Abomination
(Yeah, the Yoh thing was perhaps not the best thing in the story. It did, for my rather twisted mind, lead to some rather titillating ero afterwards though.).
I like Kouji's ending the best, because it gave us some (pretty creepy) closure. In some ways it reminds me of the normal ending inKira-Kira
(I can't even tell you the vn name without it being a somewhat big spoiler, select at your own risk).
The other interesting ending is the one where Saya blooms. I personally just can't say whether this was actually bad or not morally, because I don't know how the people who get converted eventually feel about their condition. Maybe EldritchAbominations
have a killer life? That's why I really lack closure when it comes to that route. But that might be just as well, I guess.