RWBY: Moon Reflection - Chapter 57: The Truth... According to Them

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

Warden wakes up in a wilderness with a hole in his mind, deprived of all his memories. Lost, he found within himself an aptitude for combat and magic.On happenstance, he rescues a pair of youths and an entire village, pushing him into a renowned academy of mages and warriors alike to become a teacher.Warden adventures across the divided land of Ezim, determined to unravel the mysteries of his past. However, the task becomes incredibly hazardous when his own path—the ruinous power of Void that runs through his veins—holds a connection to the Traitor Gods, who threaten to cast their shadow upon the world once more.

Xiao Rou, a girl growing up in a poor countryside family, finds that she’s actually the daughter of a wealthy couple. Her mother had mistaken another girl for her back at the hospital. Thinking she would change from an ugly duckling to a noble swan and live happily ever after with her real family, reality strikes her in the face.

The story is about a boy entering high school, who answers a strange call from a public phone one night. The caller challenges him to a bet: She’ll remove the birthmark which he sees as the cause of so many problems, and he’ll have fifty days to win the heart of a girl he’d considered far beyond his reach. And with this, a very strange summer begins.