Princess is Glamorous in Modern Day - Chapter 1013 - Phoenix Cry Wins First!  

Following her attempted assassination, Fatima found herself amidst a meticulously staged slave auction orchestrated by her mysterious rescuers in the capital city of a prospective ally empire. Now a slave of the Kartier Duchy, her life as a princess seems far behind her as she spends her days toiling the farms under the scorching sun. Just when all hopes seem to be lost, Fatima’s painful days eased upon meeting the strikingly handsome heir of the Kartier duchy along with his cold and seemingly gruff knight. Will she ever overcome the shackles of slavery and return home to reclaim her title or will spend the rest of her life enduring the cruel treatments of the duchess? Torn between a charming heir and a dubious knight as her potential escape routes, which hand will she grasp?

Octavius, misled by friends, embarks on a quest to clear his father's name, ultimately facing a tragic end with his sister.Their journey results in devastating loss, leaving him powerless and yearning for revenge against those who harmed his family. Spirits offer him a chance to reincarnate, but he refuses, saying;“What’s the point of a new life if I keep running from my problems”The entities are taken aback by his unwavering decision, having never encountered a spirit who refuses to escape their troubled past. They warn him about the evil being that now resides in his old body, but that only motivates him. He believed In the saying - to defeat a monster, you have to be twice as monstrous.Embracing his fate as The Phantom's Gambit, they traverse the shadowy path of retribution, their identities blur, secrets unravel, and the line between savior and monster fades.This is a tale of darkness and redemption, where justice is a blade, and revenge is the only way forward.

This is the story of a modern sailor who was accidentally reborn as a soldier of the Brazilian Expeditionary Force, and finally became the largest plutocratic family in Brazil by virtue of his foresight.

- Description from novelbuddy

I was proposed to by the Final Boss.