This is my first review, and I'm leaving it because this is the first time I've finished a manga on the release day of the final chapter, so it's quite an event for me!
I didn't know what I was in for with this manga but I got exactly what I wanted I think.
Overall 9: Great Manga, if you like this type of manga I strongly suggest it. It's a short read, but well worth it. It's a much more lighthearted approach to a brother/sister love story. I'll add a semi-spoiler down the bottom because I do consider this to be quite unique among the other manga I've read.

Art: 6 : because, though the character design is great and the characters are cute! it definitely feels a little off at times, and there are some dynamic scenes that do not look right.

Character: 10 : because you don't really hate anybody, and they don't act too different from how you would expect. Plus Uta is cute.

Enjoyment: 10 : because this is what I wanted. Cute romance they need to hide from the world. Plenty of fluff.

Story: 9 : It doesn't necessarily have a lot going on, just day to day for the most part, then it eventually hits some drama like most slice-of-life's do. I'm not one to want the drama to go on too long, my poor heart can only take so much pain. But siscon/brocon blows through the drama at record speed, the last few chapters feel rather rushed for that reason.

The biggest problem when reading these types of stories is they often pull out half-measures on the ending, trying to keep publishers and people who wouldn't even read this type of manga, happy. This one has the follow through to a happy ending with no half measures.

(Semi Spoiler)
Something I want to add onto the end: I feel like there's always a few special moments in manga's and anime's that'll stick with you forever. For me, in this manga it's the speech following "Uta, why do you think it is couples get married?" It's moments like that, that make this Manga rather unique to me. Most of the time incest romances involve the characters hating the fact they fell in love with their sibling, hating themselves, wishing it was different. Ritsu and Uta aren't rejecting or embracing it, but they have a different view on the situation and overall seem happy that they love each other.