well,gosho has already used this trick Araide,so i really hope that he won't do the same again4. This is just a guess: Maybe Bourbon is somebody else who appear unusually often these days (Gosho also did that too, when Vermouth disguised as Araide-sensei, he appeared really often). I think Bourbon might be disguise as Agasa (I hope not), or Sonoko, or maybe even Ran... I think Sonoko is the most suspicious, she has met Okiya at Shinichi's house, so maybe she'd ask Vermouth to disguise as Akai to lure the real one out (who's actually Okiya).
,that's also why i don't want that Okiya=Akai: a lot of people believe in this theory,including me,so it wouldn't be surprised if that happen,and what i like with Gosho is that he always surprise me!
but i'm the only one who think that it's weird to see Okiya very close to the professor?(he propose to help him for his research,he take care of the DB during ikkaku rock case,he cooks for the professor...)
I'm just hoping that Gosho will add some additional twist to it, like in this newest case where the culprit goes on to do something else...
