MTL - I Refuse to be a Supporting Character - Chapter 35

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

A new work from the author of 'My Senior Brother is Too Steady', welcome to enjoy it!-------[Science Fiction Apocalypse Setting + Alone Cultivation Protagonist, Not a Mindless Feel-Good Story]This is a shattered world where human civilization barely gasps for air on a planet ravaged by the Blade Beast catastrophe, the flame of civilization in underground fortresses flickers intermittently, and human elites in space are brewing a final plan to strike back at the Blade Beasts, but the future of humanity is dimly lit by fading stars…“So,”a Mahayana Realm expert, who after cultivating alone for one hundred and twenty-five years failed his tribulation and became a Residual Soul in this 'peculiar' world, sighed deeply as he looked up to the sky:“What the hell does this have to do with me?!”

Xu Jun finally defeated the BOSS–the Dark Demon King, in this stand-alone, virtual reality game. When he wanted to go out to browse Weibo and express his mood, he suddenly encountered a game BUG and immediately passes over to the game world.

He became the man who finally took down the Great Demon King in this world. Gratifying! The attention of millions of people!

……However, he did not know the development of this world was not the same as the game, the Demon King did not die, rather his soul entered into Xu Jun’s body; this Demon King knows of all the stupid things Xu Jun does everyday…….

- Description from Novelupdates

He was a wealthy and mysterious financial backer who had appeared before her when she needed money the most. After the courtship, she took the money and left.