Kou is a fictional character from Monochrome Factor. He is one of the Rei, and a perverted 25-year-old friend to both Akira and Kengo from an event that occurred several years ago. He has an ability to drain darkness out from other's bodies with his unusually long canine teeth, an ability he has exhibited twice in order to return Kengo back to normal. He resembles a vampire when doing so. This character is popular among cosplayers. It can be portrayed by wearing cosplay Kou costume and cosplay Kou wig. This character is always present in a Monochrome Factor cosplay.