Terminally-Ill Genius Dark Knight - Chapter 116

After dying in laboratory tests, Klaus transmigrated to a Sorcerer World, in a strange and peculiar character whose existence is an enigma. He knew this world, for it was the world of the novel one of his students wrote. He also knew the character because he created it. But it was a discarded character; it never appeared in the novel. How could he have transmigrated in it? Reality hit him soon after when he was sent to cross through the first test that every sorcerer must pass to awaken his abilities. There, he will have to fight against powerful monsters, which they call Curses, and against other Sorcerers, all to try to enter the select group of Sorcerers to discover the secrets that await in this world and understand his arrival to this and his existence. Just when he thought his journey might be boring, he received a peculiar and mighty power bordering divinity, capable of making him reach unimaginable heights. Although a bit dangerous...

This is the story of a crazy lich who possesses an internal game system and brings catastrophe to the entire world.

With a square halberd in the palm, and a red rabbit and horse under him, nowhere can the world go!

- Description from novelbuddy

On his usual way to home Mikado Tsuchio fell into a hole that suddenly opened on the ground. Just like that, Tsuchio falls in a different world, he lands on a Grappler Wyvern and manages to tame it.

Tsuchio decides just like that to live in the other world, the reason for his quick decision: he wants to make a monster girl harem.