Monsters
Even behind closed lids and facing a wall you could picture the monsters coming to get you. Gnarled limbs and caked in dirt, with pocked skin and gaping maws. You pictured a thousand of them hobbling silently up behind you, reaching out those taloned hands, curling into the fabric of your night dress- and your skin. You braced for it, squeezing your body so closely into itself that it hurt. But the violence never came, or at least it had not yet come.
Truth be told, this was your third night spent sleepless and scared. Imagining monsters and pain that would surely come. This immaculate bed, these luxurious sheets, they were beginning to feel like comfort. The men standing guard outside the room were beginning to feel like real guardians, not captors.
Your father is a wealthy business tycoon, he makes his money from his kekkei genkai. Using the wood release jutsu inherited from the Land of Fire many, many decades ago. Originally, your family's name was Senju, then Sarutobi, then they migrated and over the years it became many different things before your father's father took his mother. She didn't know this, nor did your father, your history died when the last Sarutobi of your family did. But the Kekkei Genkai was still the same. Partially.
You were the second oldest daughter of the Utsubo family, in total there were eighteen of you between six women who had all bore sons before. A testament to your father's desire to carry on the lineage. His failure as well. The problem was, due to the ‘watering’ down of your bloodline over the decades, the extremely valuable Kekkei Genkai was quite rare. It skipped a generation and even then was only present in the eldest son.
That was the case, at least until someone down the line realized that it could manifest if they had a son with the eldest daughter of someone with the Kekkei Genkai. Your father is the result of that, and now that he has exhausted his efforts at having a son, he has his eyes set on finding your older sister a suitable husband. But so do your father's enemies.
Your father has already turned down hundreds of men from many lands who want your sister's hand. Some have taken it amicably, others have sent threats, and one has acted on it as far as your family is aware. A letter came in a week ago, a note from a futile lord in the east. He spent good money with a mercenary group to come take your sister and make her his.
Your father was panicking, worried that his business would become a failure without an heir. Until one of his partners devised a plan. Tell the futile lord that he could have your sister, and give her to him, or at least make him think you did. After all, your family could finally put your wasted life to good use.
You are her slightly younger twin after all.
So your family prepped you, gave you her nice, big room, her pretty clothes and comfy sheets. They even styled your hair like hers and painted her mole on your face with the longest lasting ink they could find. Even you couldn't tell the two of you apart now.
But even with your family's promise, the futile lord was still sending the mercenaries. The money was already paid after all, and the Akatsuki never go back on their deals until the job is done.