I picked this book up before I even realised it was by Yun Kouga, both the artwork and storyline are quite different to her current manga series "Loveless", but still very very good.
The plot revolves around two angels, Chihaya and Kagetsuya, sent to Earth on a mission to observe and report the positive and negative points of humans (or "Earthians" as the angels call them) behaviour to the archangel Michael. If ten thousand "pluses" are counted the existance of the Earthian will be spared, if ten thousand "minuses" are counted the Earthian will be destroyed.
This first book is essentially an introduction to these characters through a series of sub-plots showing both the corruption and kindness of human behaviour. While each one is interesting in its own right, I couldn't help but feel a little frustrated that it wasn't getting that far into the "main" plot - the relationship between these two angels - instead it feels somewhat strung out and ill-paced. The author's teasingly slow releases of information about Chihaya, Kagetsuya and angel society make you ever more curious to read more (which is probably a good thing, I'll certainly be getting the next volume when I can!). Speaking of the characters, they are hard to dislike - Chihaya, despite being outcasted because of his dark hair and wings, is adorably optimistic and sweet while Kagetsuya is a seemingly stern angel of noble birth who has a talent for cooking and often has to fish Chihaya out of trouble.
But be warned, if you are expecting artwork like that which Kouga uses in "Loveless", be prepared for a shock. While it was probably cutting-edge in it's day (the first chapter of this manga is almost twenty years old now), it looks terribly dated now. Fluffy fringed mullet-ish hairdos, some nasty clothing choices (dungarees!) and huuuge shoulders are the main offenders. The artwork looks more like a cross between Gravitation and Angel Sanctuary than Kouga's current work. Its still very beautiful in parts, but not to my personal taste.
All in all, very enjoyable with memorable characters and heartwarming stories. If you can overlook the dated artwork and some inexperienced writing, there's a real good manga in there.