Best girl overall is definitely Aishia, but I don't see her as a love interest, nor do I think she will remain until the end, considering her circumstances. It would be great if she stayed tho.
For the harem, in order: Satsuki, Liselotte, Celia, Miharu. Optionally also Komomo, and maybe Flora and Sylvie.
Satsuki is simply amazing. In one volume, she's shown more color than some other characters in all previous volumes. Her borderline depression, the happiness at meeting Miharu, the bliss when taking a proper bath, her shyness during her dance with Rio, her strength and determination in correctly Rio's behaviour. Yep, she's a fine character and woman in my eyes.
Liselotte and Celia are both great characters and honestly they're ranked equally currently. Liselotte has the boon of her previous life. She's a hard worker, is very smart and has some nice interactions with Rio. Celia has the boon of having a cute history with Rio during the Academy days. Their interactions are really nice and she has the strongest bond with Rio. If anything, I don't like the loli status Celia has, but I can live with that if it doesn't get mentioned every other sentence, like in some other series.
Miharu solely because she is the main heroine, but I don't like her timid personality that much.
Komomo is super cute. She's too young, but there's potential I guess. I'm all for her coming to the Strahl region and having fun with Rio and friends. Even if that means Sayo coming along.
Flora is a bit depressing of a character. But I think if Rio stops being an a--hole to her, she might clean up nicely. Still a bit timid though. That being said, so far any 'love' there is for Rio is probably only because of her obsession with Rio.
Sylvie we don't know a lot about, but I am assuming at some point Rio will help her out. Her listing is purely based on her looks reminding me of Saber.
Aishia is not in there because I don't see her as a potential lover. She's great tho.
Latifa is a complete cutie, albeit a bit clingy, but she's too young for now and they're self proclaimed siblings. May change if their relationship changes.
Alma, Orphia, I can simply not see this. Sara's behaviour is cute, but the others don't really add anything for me.
Christina failed the Harem entrance exam by how she acted back in Volume 1 & 2. Go die in a fire.
Charlotte is creepy. I don't like her art, nor do I like how meddlesome she is. She seems super manipulative and I reckon she likes to wreck peoples relationships for fun. I don't believe she actually likes Rio, and even if it's true, she can go die in a fire.
Dryas would be a fun addition, but not gonna happen I guess.
Lily has a thing for Takahisa I think.
Roanna is busy keeping Hiroaki in check, and she's from Beltram, so die in a fire?
Ruri is a great girl, too bad she's a cousin of Rio's.
Sayo is a likely harem candidate (if the author didn't forget her), but I don't like her personality. Like with Miharu, she's too troublesome due to her incredibly timid personality.
So far the only likely candidates are Celia and Miharu. Celia because the strong bond between her and Rio, and Miharu because of the bond between her and Haruto.
Edit: and I agree with whoever, that Cosette would be a fun addition. Her personality feels a bit like a fresh breath of air, between all the super-Japanese shyness, without feeling manipulative like Charlotte. But in the end she's just comic relief.
