@Not_againD it's the main character, he changed his hair between chapters, the author didn't even explain it, but dedicated two or three chapters to Chizuru's period.
@Not_againD I'll try to use all my English skills to explain this... oh G**... It's common knowledge that the author has a crush on Chizuru, and he will never allow another man to have his "wife." So he uses meta-language to insert himself into the story as Kazuya. That way, he is going to end up with Chizuru in the end, one way or another...