Mechanic Butterflys

Toko is a detective at the Tokyo Metropolitan Police. Her senior officer is being transferred to another unit. However, before the transfer is completed a rich man is found killed at his house. Aside from the gruesomeness of the murder an oddity is a blue flower on the corpse. A clue is sent to a local publication. The contents seem to be playing with the police. Is it a tease, is it a clue or is it both? The police department is trying to solve the riddle.