From Onkei-kun:

These novels are an official publication, not fan-made. They were written by the show’s director, Hiroyuki Kakudou, and one of the screenwriters, Hiro Masaki. Therefore, information revealed in them can be considered canon. Notice the use of verb “can” here, meaning that it is not an absolute. You’ll discover as you read on that not everything is exactly as portrayed in the television series.