First thing:
I've played through both Near-Side and Far-side in Tsukihime, at first glance it seems MB follows the events of Arcueid's good ending (in where she does not go "zZzZz" in Millenium castle after Roa is defeated, and one year after that KT takes place) After winning against Sion in the Story-mode's first block. Sion asks Shiki to act as a mediator in the negotiations with the True Ancestor (a.k.a. Arc) and after Shiki says: "Do you think she'll listen to what I say, where did you get that idea!?"Sion says: "W-Well, you... The True Ancestor... Aren't the two of you... L-Lovers?" (After that statement Shiki blushes but doesn't object, hinting that it is true that they really are). Is it just me or is there something missing here??? If it's Sacchin's ending, then why is the main male protagonist not loving the Tsukihime-route's main female protagonist???
Second thing:
In the story of Melty Blood (and ReACT) Sacchin never appears. She is only mentioned three times in the full story (I have played all
Third thing:
With the Release of ReACT, Sacchin finally appeared as a playable character. But if you know the game's story, her appearance could might as well been a fake created by Wallachia or W. Len. ReACT also includes something that opposes the fact that this is the followup to Sacchin's normal/good end: (you might already know who I mean, so here it comes anyway) Len. Len first appeared as a plot device dream familliar in Tsukihime (giving Shiki a naughty dream after have helped Arc kill Nrvnqsr) without a name. In KT (which follows Arc's normal/good ending) the familliar is named Len and is a major character in the KT-plot (In the end, Len makes a contract with Shiki and becomes his familliar). In Melty Blood ReACT's Arcade mode, Len is portrayed as Shiki's familliar, just like in KT, meaning that KT was prior to the events of Melty Blood, pointing out that this also connects the story to Arc's normal/good ending. Also, if this is following Sacchin's end, then why has Shiki completeky forgotten that Sacchin is still in Misaki City??? (In the "winners-talk" after beating Sacchin with Shiki, he says that the person he just faced "looked a lot like Yumizuka-san..." hinting he hasn't seen her for awhile, that also hinting that she could've died prior to Melty Blood, and as we all know, she does get killed by Shiki in the Far-Side routes). Also, in ReACT, Sion and Sacchin seems to have become good friends, but they never explained how and when they met. Adding to that, in the Hologram Summer/Lord of Lies - NIGHT ON THE BLOOD LIAR route (which is the official 'true' ending to Melty Blood) Sion leaves Misaki City for the Atlas Acardemy, to resume her studies for a cure to vampirism (But this does in fact have an explanation, sort of... After Aoko creates W. Len, the event similiar to the Night of Wallachia takes place in Misaki City once more, Sion arrives of course, with her calculations showing a high possibility that Zepia might be materialized into reality again, thus explaining why she's still in Misaki City).
These are the thoughts that came into my mind when I first heard that MB was after Sacchin's end, if none can find something I have missed or prove me wrong, then all we can do is wait for the remake of Tsukihime to come out, and get translated (since I don't know Japanese). So please post something if you see that I've missed some important parts (since I tend to to do that often sometimes).
Alternative solution:
An alternative solution to the questions I listed above could be a modified good end in the Arc route. It could have the same basics as Arc's end, but include Sacchin in it too. Arc is killed by Shiki, Arc revives herself and goes to find Shiki, Arc and Shiki team up and kills Nrvnqsr, Sacchin stops coming to school, Shiki sets out to find her, finds her and is overwhelmed by her new vampiric strength, but is saved by Arc who chases her away. The story progresses, Arc's and Shiki's relationship continues to develop into love, but at the same time, the fact that one of his classmates now is a vampire bothers him, because after seing her like that, he wants to save her. In the end, Sacchin's parent vampire Roa is killed by Shiki. Arcueid is mortally wounded like in her original route, and the epilouge starts after Shiki meets up with the now free Sacchin. But Sacchin leaves Shiki saying she can no longer live a normal life. The epilogue is the same as Arc's good end with her appearing when Shiki's walking to school, but with the final sentence: "In the end, the police never found Yumizuka Satsuki... Yes, because she has left this world, a world she can no longer return to..."
This end prolly wasn't very good but if it was like this, it'd explain the Story and Sacchin's appearance in MB.