Random suggestion, but have you tried Repeat by Shirokoi? It's honestly the only one I've read that comes close to Dawn Chorus for me.
I've tried and played countless of FVNs, do you want recommendations? I have an entire collection just for "those holding a special place in my heart" numbering close to 70, I believe. Since you're new to the whole thing in general.
About Repeat: It's one of the oldest FVNs, that didn't get abandoned, with a compelling and thrilling story, but in my opinion not so great characters. However that could have changed since then, so it is a pretty good recommendation. Although I wouldn't say Dawn Chorus and Repeat are comparable.
Btw. what's your favorite genre or most important element in a VN?
(hope you don't mind reading~)
That's definitely a criteria that is important, unless unique means just different and not different from most/all other characters or love interests. Therefore Tyson was/is my favorite love interest of any FVN, who is basically best friend friend, not literal dad and lover all at once for the MC. Backstory isn't really important to me, because characters have to be more than 1/2 dimensional from the start to keep me invested in the first place or the story is intense. You could say a backstory adds depth, but I think it can also be cheating.
The best gay novel trilogy I ever read has the greatest characters of any story I know. Everyone is unique and interacts in a believable way. Their backstories are very intense.
I don't mind a well written sex scene, but it's hard to get them I feel like and can even ruin a FVN (creator too) in my case with Tennis Ace. Romance is always welcome, if it is introduced correctly and executed in a natural pace. Some FVNs such as "cute'n fluffy" (forgot the name) completely fail or ridicule this crucial aspect.