I Became the Villain's Trainer - Chapter 10

I was summoned to a ruined world and received the ability to create various things. Since I don’t have a house to live in I will make a house. Since people are gathering at my house I will make a town. Since the town is being attacked by monsters I will make the strongest weapon and repel them. Using my infinitely charging magic power I will remake this world as I please.

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

MC Derick, unexpectedly reborn, had thought he could save his sister's fate, whom he had relied on since childhood. However, to his surprise, an apocalypse unfolded...After accidentally killing zombies, Derick activated the Apocalypse King system. Wasn't this forcing him to conquer the world and establish his own ideal kingdom?Thus, Derick embarked on the path of an Apocalypse King, singing all the way from the city of Gray Bear. Want to survive? First, call him “Master.” Whether you are a high-ranking lady, a celebrity singer, a police flower, a school belle, or an elegant beauty, in Derick's eyes, you are merely a slave. To stay alive, behave obediently and serve as a good female slave...

My brother* and I, from elementary school to university, had grown up together. We didn’t just get into the same degree, we’re also sharing the same dormitory room.