It had tonnes of loopholes. Okay, maybe we have to watch it remembering that it has no connection what-so-ever with the Main storyline of the anime. But lemme pick out the loop holes:
1) Otome never meets Sekai till the 10th Episode and there we have them all in the same Hot Bath and in the restaraunt at the same table.
2) By then (1oth episode) I doubt Sekai really likes Otome cuz of the intercourse Otome had with Makoto - with all that video stuff being done.
3) If you need to place the OVA anywhere in between the 12 episodes, it's impossible, cuz if it comes in between the first 6, then Otome should never have been there besides Sekai, and if it comes in the lattter 6 Episodes, then Katsura would have never invited Sekai along, or Setsuna.
4) Valentines shit - Katsura is shown as a good cook. :| She made something which so turned me off. I wonder how anyone even FOUND that remotely funny.
5) Makoto's place had changed. He was not sitting besides Sekai.
6) Sawamura (that's his name, right?) has a crush on Makoto? Wtf. That is so not funny :|
7) Where did Sekai's mom come into the picture, too?

Oh! Almost missed this: Kokoro never meets anyone till the 9th Episode. :| Then how is she in the same Hot bath :|