The Hero Stole My Throne as Demon King

One day, my childhood friend and I were summoned together to another world of swords and magic.

I was to become the Demon King, and he was to become the Hero.

God said our personalities were perfect for those roles.

I said fine. I hated that human trafficker, but the casting made perfect sense.

He didn't say a word. In the final second before we transmigrated, he suddenly shoved me aside and entered the Demon King's summoning circle.

He stole my place as the Demon King.

God said that meant I had to take his place as the Hero.

Me: ?

Me? Become the Hero? Are you serious???

Note: The main story is told in third person.

Theme: If you can't change yourself, then change the world.