I'm the Bad Guy!?: Arrival (I'm the bad guy!? #1)

Our hero wakes to find himself if the body of one of his favorite Isekai anime characters. In this new world, the hero is a once in a hundred-year prodigy, a master Arcanist, and is blessed by the god of magic himself!
He has a harem of beautiful women at his beck and call, an Empire under his control, and the most powerful Arcana Spirits the world has ever seen.
Sounds great, right? Well, there's just one problem... Our hero isn't *the* hero.
Our hero is the bad guy with a tragic ending.
Armed with only his knowledge of the anime and the body of twelve-year-old Aren Ulvani. Can our hero turn his life around or will the events of the anime come to pass regardless of what he does?