Rui x reader - Promises

Chapter One - Ten Years Ago

Authors note! - this is the very first story I have written on wattpad, first fanfiction as well. If there are lots of errors or the format isn't good, please tell me so my future stories may be better!
Enjoy!

"Kioti, Y/n, come inside!" your mother called.

"Yes, mother!" you and your brother called in unison.

You and Kioti trumped inside, giggling and poking each other. The expression on your mother's face made your innocent smiles falter.

"So, as you two know your father went missing a few days ago." you nodded cautiously. She continued. "Well, some nice people found him, but he's a bit different now."

Kioti scrunched up his face. "How different?"

"Do you remember the story of the scary monsters who prowl around at night and eat the kids who misbehave during the day?" Kioti nodded. "Well, your daddy got attacked by one on his way to the market the night he went missing. He lured it away from here so we would all be safe, and he even managed to survive! He... lost a leg in the process."

Right on cue, your dad hobbles into the room. A wooden crutch is hooked under his arm, a poor but able substitute for his missing left leg. "Hey, kiddos."

Kioti, a year older than you, burst into tears. He fully understood the situation. You were still more aloof with your young age, and were simply over excited to see your dad again. You ran to him to give him a big hug, until you saw the scabbed up wound on his other leg. You stopped running, and sat down on the ground. You stared at the wound. The shape...

"How did you survive an attack from one of the Twelve Kizuki?" your words formed on their own. Your mother gave you an alarmed look.

"How do you know about those?" She gasped. You blinked. "Did I just say something?"

Then, a young voice sounded from the door. "Sorry for interrupting. But did that girl just forget that she spoke of the Twelve Kizuki?"

Your mother looked up at the door. Standing there was a boy, looking to be around 13-14 years of age. He was wearing an outfit similar to one that you'd seen your uncle wear all the time, but he had loose sleeves and the pants were loose as well, more resembling a robe. It was a bit more teal colored than your uncle's was. He had long, straight black hair that ended in mint green tips around his waist. Two clumps of his hair protruded from the sides, and he had very unruly bangs. His eyes looked empty, a glassy mint color.

Your mother glanced at his outfit, and his sword. "I believe she did. To what do we owe the pleasure of the company of a demon slayer?"

The boy looked a bit surprised. "Oh... you know about us? Well I was..." he trailed off. Then he blinked and continued. "Ah, right. I was told to head this direction and find a girl with H/C hair, E/C eyes, who has visions of the Twelve Kizuki. They were talking about your daughter. I'm supposed to train her to become a demon slayer.... Or was it to bring her back to headquarters? Both?" He stared off into the distance.

Your mother thought about this for a moment. "I'm not too sure about this... my brother was a demon slayer and he was brutally killed on Mount Natagumo. I don't want my daughter to follow that path. Who are you anyways?"

The boy blinked. "Oh, right. My name is Muichiro Tokito, the Mist Hashira of the demon slayer core."

"A Hashira?" your father exclaimed. "They sent a Hashira to get our daughter? Honey, it must be important."