I've always been a little put-off by preliminary reviews. This is only the second preliminary review I've written (due to dropping a series or putting it on hold), and I urge you also to take it with a grain of salt, keep in mind that I can't give you a full view of the series. But this is what I got out of the first volume.
Volume one introduces us to a lot of really good ideas. Enter Kai, a young man moving to a new city in search of his lover's killer. This city is run by two rival gangs, the Mynah and the Sarte. (Kindly excuse any discrepancies between the translated and original names; I noticed a few differences in the description on this site and the way it was translated in the volume I read.) Kai gets himself a job as bodyguard-in-training for one of the "four kings" of the Sarte group-- another young man named Lahti who he's seen wearing a ring nearly identical to the one Maria-- his past lover-- wore. Shortly into his time as Lahti's new bodyguard, Kai hears an interesting rumor-- that Lahti Bara is gay. And so this potential assassination turns into a seduction mission.
All of this gave Blue Sheep Reverie a really good start. But there were quite a few red flags in this first volume too. (And I would like to reiterate that I've only read volume one, so I don't really count any of these to be major spoilers.) To start, it felt very rushed. I'm used to reading longer series, so I thought there was a lot of potential for a 9-volume series with this plotline. But that seduction/assassination plot is played out within volume one. It is almost laughably easy for Kai to get into Lahti's bed, and then his plot unravels quickly afterwards. And Kai's initial reaction to his rejection is to be... unreasonably hurt. I mean, the only time they really spent together was when Lahti was training him, and after revealing that he snuck into the Sarte organization to possibly assassinate him? At that point, Kai should be grateful he's still alive.
To be honest, this first volume was a series of up and downs for me. One minute the plot kept getting more and more interesting, the next all the plot points were being executed very poorly. Turns out Maria's still alive. She's actually Lahti's twin sister Bihaan and faked her own murder, deepening the plot a bit. Except... Lahti claims the only reason he's gay is because he can't be with the one woman he loves... his twin sister. Yup... they went there.
So at this point, I'd say it's a pretty even split between the things that give this story the potential to be great, and the things that have me worried this story is about to go downhill fast. I probably would continue, except there are so many other manga series clamoring for my wallet at the moment. So I'm going to leave it on hold for now. And possibly revise this review sometime in the future.