Originally Posted by
https://www.tsukikan.com/misc/kara-no-kyoukai-movie-nasu-kinoko-interview.html
Nasu: The actual writing of Kara no Kyoukai is a pretty embarrassing memory for me—suffice it to say it is a work that represents my true self at the time. I wrote it at a time when I felt I could take on the world armed only with my words, and I realized [through this movie] that the farther removed it became from the written medium, the more distant it became from what I was actually trying to express. So as successful as it was, it was on a different path than what my past self was trying to take with it, and it just didn't match up. Yet in seeing up through the fourth chapter, I came to realize that although I was on a different path then, it doesn't mean that I didn't leave some pretty good things behind. As the movie versions have allowed me such realizations, I was again reminded of the real value of Kara no Kyoukai. My heartfelt gratitude towards that period of time has been thus manifested into Future Gospel.
—So the driving force behind Future Gospel was that feeling of gratitude of yours.
Nasu: When I wrote Kara no Kyoukai, I felt resistance towards so many things—society, entertainment, culture—and it was my motivation to write the story. Now, I am thrilled to be writing from a place of gratitude, though with just a touch of sadness. It feels like the old Nasu Kinoko has passed on. I suppose you could say I've gone under a heavy detox, and feel much more virtuous now (laughs).