"A Fallen Angel is one who has broken the Angel's code - a criminal."
During the three weeks Neku was playing, Sanae Hanekoma was the Fallen Angel, which was implied upon heavily in the Secret Reports. Mr. Hanekoma can be considered a Fallen Angel because he revived Sho Minamimoto. He revived him in order to defeat and take over the position of the Composer so that Shibuya would be saved. Various other reasons are also mentioned in Secret Report 11.