I forgot the Title

I don't remember the name, but I remember reading the story long back, where two students dream the same thing it was a very short Manga. So the plot starts with girl dreaming of of a prince she is about to marry and when she is woken up she sees a new transfer student and calls him ouji sama by mistake, this is what I am not sure either a transfer student or her classmate, later they both have the same dream together now they wake up in the body of Prince and Princess on the wedding night they were poisoned now they've to figure out the killer and return to their own world