MTL - Abyss Domination - ~ On fairness, brushing tickets, tearing. (on)

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

I am merely a reviewer, albeit the products I review are slightly different. For example, I review quantum computers, artificial intelligence, anti-gravity mech armor, planetary engines, sublight colonial ships, stellar detonators, etc…

After I defeated the Demon King, I was executed for false accusations by the heroines.When I came back to life, this was the first thing they said.“I know it’s shameless, but would you help us one more time? Without you, the world will be destroyed.”…Would you help them if you were in my shoes?

After choking to death on a watermelon, Rong Jiahui thought that she would enter the netherworld and be reincarnated.

But when she opened her eyes, she discovered, to her very horror, that she had returned twelve years into the past…

Looking at the beautiful and awkward “little brother” that would be conferred the title of Marshal in the future for outstanding military service, she almost let out a snort of laughter.

She firmly decided to hug the thigh of this little brother, and climb to the top of her life!

The plan was beautiful, but it had just one problem.

Why had this little brother… suddenly turned into…

A little sister…

- Description from Novelupdates