I don't usually heed shoujo at all, but out of boredom I decided to check the first chapter of this series to pass some. By the time I got to chapter 4 or so I was completely glued to story. I even pulled out some full nighters, carefully & slowly reading the raws for untranslated chapters, being really interested on what's going to happen next.
Also, while this project is listed as "active" in Shoujo magic there hasn't been a single release in one year. I suppose that the forbidden theme & the huge amount of drama + suffering that's yet to come to the characters doesn't alure the scanlators to bring out a chapter every two weeks.
Since the series really doesn't seem to be completely scanlated any time soon, I'll throw in comments about the ending (from here on the post will be a spoiler, however I don't know how to tag it, si I hope some moderator will properly do so later).
From volume 9 to the ending the main focus of the series is shifted to their mother's (Yuka) efforts to separate them, the siblings eventually become so feed up with their predicaments that they reveal their relationship to the guests of their omais right in front of the church, trying to break their marriages with Ren & Kyoka, but their mother still won't allow them freedom; the kids secretly agree to meet in Rome to escape from it all. When Kasumi arrives there she can't find Yoshiki, and gets contacted by the police with the message "we need you to verify the identity of a corpse". Kasumi suffers greatly while gathering strength to even see the corpse, sulking in denial... Funerals for Yoshiki are held in Rome and Kasumi breaks up all ties with her mother & every body else, wanting to stay in Rome permanetly.
As some of you my already have guessed, in the aftermath of the service & when everybody is gone, Kasumi was still suffering about this in the place where she first meet with Yoshiki, at which point he shows kissing her, revealing how he used some aquitances to fake his deadly accident, with that said they finally embrace each other enjoying the knowledge that now no one is standing between them, Yoshiki doesn't miss the chance to kindly whisper "I love you". The next scene is a portrait of their marriage, being exhibited as propaganda in a store that sells bridal items.