Blood Keeper: Rise of Fate Control - Chapter 36: Greedy Merchant

As a corporate drone, Ashu was transported to another world, hoping to live a life free from societal pressures.However, he quickly found that even marrying a village girl would cost him half of his wealth!Fortunately, just when things were looking grim, his childhood sweetheart—who had trained for many years—arrived to fulfill their childhood marriage pact. Not only that, Ashu activated the Crit Refund System, which allowed him to earn rewards by binding with beings rated over 90 points![Binding with the Witch Childhood Sweetheart, 10x Refund on Magic Potion, Host Gains: Forbidden Water (S)][Binding with the Forest Elf, 10x Refund, Host Gains: Infinite Stamina and Infinite Recovery][Binding with the Demon Huntress Nun, 20x Refund, Host Gains: Demon Slayer Holy Crossbow (SS)][Binding with the Imperial Princess, 100x Refund, Host Gains: Sigh of the Heavenly Father Spear (SSS)]Ashu: “The refund multiplier increases as our relationship grows? I’ll definitely have to dive deeper into this!”

Amidst a disaster, an orphan contracts a sickness.

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

In Academy City, magic and science coexist in an unwavering power struggle. Toma Kamijo, an academically-challenged student in Academy City, wields the power of the Imagine Breaker in his right hand, which allows him to completely negate all supernatural powers – as well as his own luck. When he happens upon a mysterious nun named Index, whose mind has been implanted with the Index Librorum Prohibitorum – 103,000 ancient texts banned by the Church – Toma’s luck is about to be pushed to its limits when he finds himself in the middle of a war he never expected!