Arifureta Shokugyou de Sekai Saikyou (WN) - Chapter 455

Miguel transmigrated into the Wild Beast World in the body of a useless teen with the same name as himself after he was betrayed by his disciple, the Harem Emperor, for a knowledge and universal secret that he recently uncovered.In the Wild Beast World, humans could contract Wild Beasts through their Summoning Grimoire, a mysterious book that fated individuals can awaken at the age of 18.In this world of summons and beasts, Miguel awakened with the Beauty Sign-In System, which allowed him to contract legendary beauties as long as he signed in at a specific location.On his first sign-in, he received the Holy Daughter of the Red Family, the Fiery Empress of Legend.Using the Wild Beast World and the Sign-in System as a starting point, Miguel swore to return to the Immortal Cultivation World and settle scores with the Harem Emperor once and for all.Follow Miguel's journey as he reaches for the apex, becoming a legendary figure in all worlds.

In short, MC inadvertently created a world, but as the creator of the world, he did not know the world at all. He should have lived here like a fish in the sea with some plug-ins that MCs always have. But now he is even stumped by the bugs in the instant world. Luckily, in this world he has found his shadow guard, or his lover? So the daily adventure is getting not so boring…

- Description from Novelupdates

“What kind of guardian would you want to be? the one who destroys everything or the one who protects everything?”

Jason, one of the many casualties during a nuclear explosion gets the chance to reincarnate into another world due to his deeds during the war.

He gets tossed to another world due to ending up with the Shadow god as his patron, something deemed impossible.

With a system to guide him in the world of Clover and a family jinxed through the generations, his adventurous life in new world begin.