Sou Hiyori, likes to be called Midori, is a cruelly mischievous man shrouded in mystery. He seems to have somewhat sadistic tendencies; deriving happiness from teasing and harassing others for his own amusement, even in life and death situations. He enjoys making others uneasy and playing inappropriate jokes on them. He is rather controlling; His energetic and playful manner of speaking is often completely contrary to the dangerous circumstances of their situations.