Yeah, so, the first story is really infuriating for so many reasons. It's just stupid. I like possessive, controlling and sometimes even cruel semes, as long as I know they are acting that way out of love. But that's not the case in this story. Shingyouji is just a total jerk who, even though he says he's in love with Aya, also says that he's sleeping with other people. What a charming kinda guy. And Aya irks me too. I liked him at first, his arrogant and strong personality was a nice change for an uke, yet all of a sudden he turns into a wimpy mess, who can't live without the other guy. I did start to like him again at the end of their story, when he finally does seem to fight back, but ultimately I was left feeling disappointed as all the major issues in their relationship were just glossed over. I mean, what happened with the whole fiancee thing? Did the other guy get married then or what? And does Shingyouji continue sleeping around? (There are times when I got the impression that he doesn't - for instance when his assistant tells that actress that he no longer has time to mess around with anyone, except for the "wildcat", and in the extra chapter he does turn down an invitation as his "cat" is waiting for him. But if that's the case, then why did he tell Aya that he was still bedding others in the first place?) And why is this labeled as S&M? There was barely any. The seme restrained the uke a couple of times, constantly forced him into sex, and just treated him badly overall. -- That isn't sadomasochism, that's just the seme being a dick.
The second story, however, is much more interesting. Both the seme and uke have really strong personalities and they are both quite complex characters. Unlike in the previous story, I can actually believe and understand both characters' feelings and actions.
There is rape in the first(?) chapter, but it doesn't lead to "love", and is dealt with quite well. And there is also violence, but both characters are equally violent to the other, so it's not like one guy is constantly beating up the other. Plus Rinka actually gets turned on when sensei hits him, so that makes this even better. But if you're not into that kind of thing then don't worry, it's not all about fighting. There is love too, or at least one-sided love for the time being (I've only read upto chapter 13 so far), but it's not all depressing or angsty, as there are some funny moments mixed in to keep it relatively light. For instance, all of Rinka's interactions with the other hosts are quite amusing XD I really like the dark-haired guy (not sure of his name), especially when he messes with Aya.
Another good thing about this story is that the uke is not only strong and independent, he actually enjoys and initiates sex too. Plus he's older than the seme, which I think is hotter.
Overall the art is decent. It's nice and clean, and all the guys look like guys (which I like -- I'm fed up of seeing either overly feminine men or bordering-on-shota type characters), but for some reason it doesn't appeal to me that much. I can't quite figure out why. It's just average really. Unfortunately that does mean that the sex scenes are a little bit dull too. Don't get me wrong, they aren't bad at all, they just seem to be lacking something. Though in the more recent chapters they have improved, but I still haven't been wowed yet. So if you want to read this just for the smut, then I'd advise finding something else to get your jollies off to. But if you want an interesting plot, with likeable and complex characters facing actual problems (like struggling to get someone to reciprocate your feelings, instead of the typical silly misunderstandings in most BL), then this is the story for you.
So just skip the first volume entirely. You really won't miss much, believe me. The only thing you need to know is that Aya, one of the hosts working with Rinka, is the guy from the first volume. And the person he always talks about is obviously his "lover" (I'm still cynical about their relationship so I'm not going to class them as being real lovers, it's more like a slave x pet type of thing). Aside from that there really isn't any other connection between the first and second stories, so just skip to the second volume. Unless you like wasting your own time.