Hiroki Dan is the main antagonist of "Trace: Kasouken Houi Kenkyuuin no Tsuisou" and the main protagonist of his spin-off "Brutal: Satsujin Keisatsukan no Kokuhaku". He is a highly ranked police investigator and a serial killer. Dan is part of the Investigation Division Unit 1 and the son of a former police superintendent General. He seeks out criminals who could not be convicted by the law, and kills them. According to his own testimony during a confession in a church, he admits to doing this mainly to perform good deeds so that he can see his deceased friend again in heaven. He strongly tends to extremes and not only kills his victims, but makes them suffer in the most heinous ways. Dan even takes pleasure in it, so much so that he often doesn't notice that his victim has long since passed away. In the end, he photographs each of his victims and then keeps the photo in a photo album.