Honkai Impact 3rd: The Dark Lord

[Transmigration + System + fanfiction + invincible protagonist + multiple heroines + a little OOC + absolutely no breaking up any male-female CPs centered on Siegfried and Cecilia]

A boy sharing his name with Ryuga from Kamen Rider Ryuki arrives in the world of Honkai Impact 3rd through an absurd twist of fate. He transforms into Dark Kiva, protects everything beautiful in the world, and ultimately becomes a king.

(I’ve read lots of books and found very few about Kiva. Even when I did find one, updates were slow or it had been abandoned outright. So on a whim, I decided to write my own Kiva-centered Kamen Rider and Honkai crossover. This is my first time writing a book, and I’m not sure if I’ll be able to stick with it, so I hope everyone will support me. Besides Dark Kiva, the protagonist can also transform into Kamen Rider IXA and Kamen Rider Ryuga, but the main focus will be Dark Kiva. I may add more depending on how things go, but the main idea is for him to gain the abilities of other Riders.)