Movie of long title

I watched the movie last week.
The title is "Usotuki Mi-kun & Kowareta Ma-chan(A liar Mi-kun & broken Ma-chan)".
It is very long title.
The original story is a novel.
The movie has a trauma as its hero & heroine.
They are high school students.
It is a story that they are rolled the serial murders and kidnapping.
But this is love story too.
It was cruelly,but it was a funny movie.