When the attackers headed for Vance family home, little Lesley, took a black rifle and finished her father's late mission. A teardrop on Lesley's cheek as she shot a bullet after a bullet, each bullet killing an assassin. Tears last came when he shot the last man from rival Vance family.
Later, Lesley was adopted to become Vance family's eldest adopted daughter afterwards, also giving their sole heir, Harley under Lesley's supervision as a sister. Harley, who used to be a natural troublemaker, always used her magical powers to create a ruckus in Vance family households. Only Lesley can keep Harley in control.
After hearing that Harley had long wandered alone into the treacherous Land of Dawn, Lesley caught up with his rifle. After finding Harley from a very long journey, he realized that an immature young man had changed from various experiences. Lesley decided that it would be better if Harley was in the Land of Dawn, while he secretly protected his brother from the shadows.
From then on, all monsters exposed to Harley magic will also be attacked by a single black bullet. The stories of the prodigy followed by a mysterious sniper soon spread throughout the world.