The heroine, Tokieda Nao, discovers that she has an Unexpected Fiancé! It seems her father's company is having difficulty, so in order to save it, he set up an arranged marriage between Nao and the son of a wealthy man. Nao isn't exactly happy to hear this news. To make things even more fun, Nao is attending a new high school. Up to this point, she had only attended all-girls schools. Her new school was an all-boys school up to this year, so it is about 95% guys! Nao knows that her new fiance is a student there, but she hasn't been told exactly WHO it is! Right away Nao meets two interesting guys at school. They are the somewhat surly Sakaki Mitsuru, and the very pretty boy Toono Minori. Nao actually thought Minori was a girl at first, and was rather shocked to discover he is a guy. Nao is trying to figure out which guy at the school is her fiance, but she doesn't have much to go on, only 5 hints: 1.) One of his initials is "M" 2.) He has a mole somewhere near his hip 3.) He has a flower-shaped birthmark 4.) She met him when she was a child 5.) Fear of high places.

The hunt is on as Nao cheerfully searches for her new fiance. More than one boy seems to fit her clues, how will she ever figure out who it is?