On A Deserted Island With A Beauty - Chapter 62 - breaking out of the snake pit

The whole world is subjected to a highly dangerous standardised exam called the Global University Entrance Examination. Answering questions by putting their lives at stake, they would live if they passed the test. Every month the exam will undergo reformation while, occasionally, it is random.

- Description from Novelupdates

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates

The world is terrorized by the powerful Black Witch who has been sealed in the moon. Every ten years, the night of Hexennacht arrives and a chosen witch must battle the Black Witch in hopes of finally defeating her.

As the current decade’s Hexennacht approaches, a mysterious girl named Kagami Kagami arrives and meets Horinouchi Mitsuru, the daughter of the previous Hexennacht representative.

It takes place between Kyoukai Senjou no Horizon and the City Series, two other series by the author.

ln the Higher Realm.{Ehhh! It’s started?} an entity exclaimed.{Yeah, but like, what the hell—she gave the golden finger to him? Of all people, someone useless and a scheming bastard?} another shot back, clearly not having it.{Someone Immediately Stop him he's corrupting the system!} An entity roared before they could even get ready for see how had had been chosen!___On Earth.[System Integration... 1%A wicked grin spread across his face. This was his chance—a chance to do something no one in those web novels and mangas and animes had ever done. To corrupt the system!minute later....[System integration... 85%...][System integration... 99%...][Integration complete!] It ran one last time...“Did I succeed?”And so the journey started.