Thanks again for your reply. In fact, the recommendation from The Red Room thread was the main reason why I paid attention to this game in the first place. I was particularly interested in a character similar to Mia, but from what you've said, this game doesn't have a direct equivalent. I think I'll hold off on playing for now until the story progresses a bit and goes beyond the prologue. I wish you luck, but I'd rather be pleasantly surprised than disappointed like I was with Alishia's game.The Red Room is one of the inspirations for this VN, yes. But the story and characters here are still their own thing, so I can't really answer your questions about who is who. Ashe (the protagonist) is not in a relationship when the game starts, and it's hard to say what constitutes as "further" here.
Maybe you should give the game a try and find out for yourself?