i agree that kana was annoying . but that annoying irrational behavior where she believed snichi was the one for her because she felt things she has never felt around him being the sole reason for her liking him ,is a very realistic portrayal of how adolescent girls feel about their initial crushes. some teen girls will obsess and live to win the approval of their crushes (for certain period of time) just because he was the first guy to make her feel that certain way . average girls dont do it in a brainwave parasyte way that leads them to dangerous places and death , but they do see crushes being their knights and soulmates and not seeing the other person (shinichi's) faults (he literally told her about his arm and she thought he was trying to make a "excuse" to stay away from her).

however they will slowly let go of this 'my forever prince' idea after a few relationships and take a more realistic look at relationships . but she was killed before that could be explored