Luna

Age: 16 Height: 164 cm Silver-haired girl from Arselia born into poverty who became a vicious killer in her fight for survival and was consequently recruited into the Guild of Darkness, an organization of professional assassins, where she became famous as The Headhunter. Luna is often lithe, and quiet like a wild cat, in a hostile environment. [spoiler]She is hired by the realm's first prince Reigar Von Arselia to eliminate his stepsister Lexia Von Arselia, but upon encountering Lexia's protector Yuuya Tenjou, she falls in love with him and rethinks her way of life since she is aware that the Guild of Darkness will send assassins to kill her for failing her task. Due to her failure in her mission, she was dismissed by Guild of Darkness and no longer a part of Guild. She became a personal bodyguard of her love rival, Lexia to redo her life.[/spoiler] (Source: I Got a Cheat Ability in a Different World Wiki)