This DMC4 two-volume novel is available only in Japanese and is written by Morihashi Bingo and a for-novel-only assistant Yasui Kentarou.

Important note: Morihashi Bingo was the scenario designer for DMC3 and 4 but he has now quit Capcom and is currently working as a free lancer. This novel is one of his free lance works so it's really up to you to decide whether the revelations in this novel are canon.

However, Bingo declared in the afterword that there were many scenes that were intended to be included in the game but which didn't make it to the final cut due to various production reasons, so he added these scenes into the novel to "complete" the story.