ルナ (Luna), also known as ルーナ・ルーラー (Luna Ruler)
One of Arai Nobu's earliest original characters. She is also a main character from "Gear of Aeris", one of the artist's original universe/story. Her character profile is filled with 8th grade diseases[1].
She has pink twintails, bandage over one eye, red tattoo and flat chest.
[1] Pixiv Encylopedia: Chuunibyou