One Piece Luffy's sister: Your Guardian Angel

Leaving Alabasta +(a new crewmate)

Mikasa and the rest of the straw hats were fast asleep.

Flashback/Dream:

"Mikasa, please. Promise me you will protect Luffy and take care of him." Her mother says.

"You will be a Great Marine someday. You are not afraid to help and protect others. You fight for justice." Her Granddad says.

Crocodile was about to stab Miss All Sunday again but Mikasa ran between them and grabbed his hook.

"You are standing? Call me impressed." Crocodile said smirking before his smirk vanished. He looked at Mikasa and his eyes widened slightly.

Her hair turned white, she had ice blue marks around her face and her eyes turned grey.Everything around her started to freeze and the ice came closer and closer to Crocodile.

"You should pray that my brother arrives here before I end you." She said as her grey eyes started to glow.

The fire surrounded her and every single bit of fire in the area was coming towards her. Her eyes looked like they were glowing red even though her eyes are brown. It's like her eyes were filled with fire.

At this moment Mikasa didn't look like a human... she looked like a real monster ... she looked like a demon.

"How dare you make Nami cry?!" She screamed angry glaring at Arlong.

"Luffy! Stop!" She yelled and suddenly lightning strikes Buggy as he was about to execute Luffy.

"Your power is strong and dangerous. You can either protect with it or kill and destroy with it." Granddad said.

"The enemies don't underestimate you," Zoro said.

I am a Monster. Mikasa thought in her dreams. 

I said my power can't hurt the people I care about ...as long as I can control it.

"Mom!" a small Mikasa yelled and fire surrounded her.

flashback end.

Mikasa opens her eyes and sits up.

"Mikasa!" She hears someone yell and tackling her.

"You finally awake!" Luffy yells as he hugs her tightly.

"Luffy! Get off her. I need to check her." Chopper says as he walks over to check on Mikasa.