Novel's Demon

I've died. However, it wasn't the end. Somehow... I woke up once again though not in the world I knew but in a world of a fantasy novel I've read in my first life. Unfortunately, I wasn't reborn as a Main Character, a supporting character or even an Extra... No! I reincarnated as a weak and useless Demon. However, this was not even the worst part... 'Why the fuck am I stuck in the Academy!?'