Sharing this article I found.
人気マンガ『鬼滅の刃』の小説版がシリーズ累計で100万部を突破した。ライターの飯田一史氏は「『人気マンガの小説版なのだから売れて当然だろう』と思う人もいるかもしれない。だが、それは違う。集英社がこれまでのノベライズの常識を大改革した結果だ」という――。
president.jp
Quick summary:
-KnY novels have sold over 1 million copies (the fastest novel to reach this numbers from Jump J books)
-They said since 2005, they had red/low numbers.
-D gray man novel (dunno which one of them) saved them.
-Also its pretty normal to get novels based on popular manga, but it's pretty difficult for them to reach 100,000 copies sold.
-They said that they had a very low record in sales, to the point that they wouldn't place the novels next to the manga volumes.
-Now after KnY novel's success, they would place them next to manga volumes (this means that with this success, they have now regained their trust over other works).
-This department that is in charge of the novels, works together with the mangaka:
- There are two groups: the editors + mangaka and the editors + the novelist. Both editors are in contact, and the ideas that the mangaka have that can't be added into the main story because it can ruin the pacing and that sort of things, those ideas are taken by the editor's novelist and with that, the novelist will start working on them.
-They said they had this losing streak with the novels because they weren't "Canon" and they didn't include illustrations from the mangaka that would attract the readers.
-Now with this new system, they look for the novelist to be fan of the work, in order to deliver an accurate work.
-They take the mangaka's own ideas that couldn't use in the main story, and this way they are motivated to draw some scenes that would have loved to include but they couldn't.
I hope you find this interesting.