A few months after Y/n, Ace and Luffy lost Sabo, the little rubber boy watched as his older sister was chopping down trees with her diamond covered fists.

Luffy: "Hey, Sis Y/n?" He spoke up as the young woman stopped her punches to look over her shoulder at him.

Y/n: "Yes, Luff, what's up?" She asked while clenching and unclenching her hands to work the numbness out of her veins.

Luffy: "What makes a great pirate crew?" He questioned as the diamond on Y/n's hands receded away to show a slight bruising.

Y/n: "Well..." She said before walking towards Luffy and lifting him off of the tree stump to place him in front of her. "You'd need a first mate, a navigator, a chef, a marksman, a doctor, a shipwright, a musician, and a helmsman. Anyone you want to have really." She said while motioning for Luffy to make fists as she held her right palm up for him. "But, first you have to get stronger and grow up, Luff."

Luffy: He pouts angrily but it made Y/n laugh even as he began throwing punches onto her open palm. "Then I'll get the best for my crew so I can become King of the Pirates!" He vowed to her

Y/n: She smiled down at her little brother before her hand shifted into pure raw sea stone prism which made Luffy weaken a lot. "Geez, Luffy sorry!" She said worried as she shook her secret off of her hand before putting Luffy at her side as she showed him the proper hand to hand combat stance. "King of the Pirates, huh?" She asked while punching her right hand forward as Luffy followed her example but poorly. "You'll have to get a strong crew to beat me one day, Luffy. I'm going to the sea first, and I'll become Queen of Pirates." She said before her hands coated themselves in f/c armament haki glittering with diamond and pulled her arm far behind her. "Diamond Hook!" She shouted out while swinging her fist forward toward the tree she was punching earlier.

A strong gust of wind blew back her h/c hair, Luffy's hair and nearly his hat as his jaw slacked onto the grass when the dust was blown away to reveal ten down trees behind the one in front of the two.

Luffy: He shook his head rapidly to look over at his big sister as she raised her fist towards her mouth the blow the steam coming off it away. "SO COOL, BIG SIS!!!" He exclaimed out in admiration as he jumped onto her back smiling. "Teach me how to do that! Teach me how to fight like you!"

Y/n: She laughed before putting her hands behind her to carry Luffy piggyback style back to Dadan's hut to cook up lunch. "Let's go back to Dadan's so I can make lunch first then I'll train you and Ace afterwards how's that?" She asked while Luffy just gave her a huge smile and nodded. "Hey, Luffy can you promise me something, it's important."

Luffy: "Promise you what, big sis?" He questioned while Y/n walked back towards Dadan's hut from the forest, once there Y/n set him down onto the ground so he had to look up at her.

Y/n: She slowly took Luffy's straw hat off of his head to spin it on her forefinger by its rim as Luffy's eyes sparkled. "I want you to keep this hat safe not just Shanks but for me." She said before placing the hat back onto his head smiling. "I'll be cheering you on, Monkey D. Luffy while you start your journey to become King of the Pirates." She said while Luffy surprised her by suddenly hugging her legs.

Luffy: "I will and when I'm strong with my own crew beside me, I'll come find you to show you how much I've grown up!" He exclaimed out as Y/n ruffled his head as he smiled up at her. "I'll be chasing after you, Big sis!"

Y/n: 'This hat has such a great legacy first dad, Shanks, and now you, Luffy.... I believe in you, little king so make me proud!' She thought while walking into the hut as Luffy followed after her shadow smiling.