Reincarnated As The Villainess's Best Friend

[WARNING] [Minor sexual descriptions of a slightly perverted MC] [All characters depicted are above the age of 18] ********** The world ended in chaos, and I died trying to save it. I was Drey Belford, the most powerful mage in the world, but even I couldn't stop the evil villainess from destroying it. Now… I’ve woken up. Fifteen years in the past. And somehow, I’m not me anymore. I’ve been reincarnated as Rin Stormborn, son of a high noble... Best friend to the girl who destroyed everything. Armed with all my memories from my previous life, I’ve been given one last chance to change the future. All I have to do is survive magic school, navigate through dangerous noble politics, and keep my best friend from starting a world-ending apocalypse. Seems pretty easy. What could possibly go wrong?