Have you ever had the experience of eating an entire bag of chips in one sitting? They look so tempting on the outside, and you just know that once you bite into one you'll be rewarded with that crunchiness, and saltiness, and all these big promises of flavor. Then you take a bite, and it doesn't live up to what you wanted; so you have another, and another, each time hoping that the next mouthful will finally bring you the satisfaction and joy that you anticipated; and you don't stop until the bag is empty?
This book is sort of like that.
On the one hand, it deals with some of my favorite themes (gender identity in love); but on the other it indulges in some of the weakest cliches (sibling-lovers, to ratchet up the "forbidden love" angle; overly age-gappy relationships, maybe also to increase the 'love conquers all' wrongness-rightness factor?) in a way that I think frankly detracts from the story. In addition, the basic premise--the title premise--Sayuri's sister being an angel--goes almost entirely unexplored for the majority of the series. It's kind of a story hook that immediately becomes a complete afterthought, and the real implications (or even the fact that there must be real implications) aren't even touched upon until the very last couple chapters.
So what we get is a fairly bog-standard slice-of-life between the standoffish and not-really-into-it depressive-withdrawn normie and the overly enthusiastic demi-human imouto. A combination of boring and exploitative. We don't have a lot of challenges to drive the plot, other than ones internal to the relationship (Sayuri trying to figure out how she actually feels and whether she reciprocates her sister's feelings). Later on, as she begins to develop some insight into this question, challenges do appear: first in the form of another character with an obviously sinister agenda--there's enough of a feeling of genuine menace that this had me seriously concerned for our mains--and then in the form of a rule change that imposes a time limit on the life whose slices we're being shown (and which might have just come from the publisher).
There is a nice romance between two side characters that does explore gender and the meaning of love between women. It goes through an ultimately satisfying arc that will probably leave you wanting to smack at least one of them repeatedly before it's over, but it is a rewarding story overall.
All in all, though, the overall feeling of the manga is a lack of direction. Roughly half the series is paint-by-numbers and can't really decide what it wants to be or where it wants to go. Then when we get around to exploring the meaning of the main conceit, the series is over in a flash, without a satisfying resolution (as far as I'm concerned) and without having ever really decided what story it wanted to tell. I must confess, though, that I read this all in one sitting, staying up far later than I should have. This was roughly equal parts serious dramatic tension and investment; and mindlessly eating the chips. But the fact is it did keep me up late wanting to see how it ends, so I have to give it points for that at least.
All that said, the art is pretty good, and it is a somewhat interesting story hook. So if you're interested in incestuous age-gappy yuri relationships with demi-humans, maybe give it a go?
