Gun Princess: Sincerely Night

Delve into an epic fantasy alongside Ambrosia, Cedric and Elwing as they quest for the ultimate weapon in a magical world ravaged by war! Long ago, mankind's foolishness angered the gods and they were stripped of their magical abilities. Unwilling to accept this loss, however, humans discovered a way to seal magic into bullets. They regained their powers... and the world was again plunged into an era of war and chaos. Now, amid the turmoil, a youth called Cedric, his sister Elwing and their companion Ambrosia set out on a journey to recover the "Gun Princess," a weapon powerful enough to change the destiny of the entire world. (Source: Seven Seas Entertainment)

A timid boy named Zao Ci, which was accepted by Mateliya, a Demon as her "number 2". He was always called an idiot by Mateliya. He is so weak that he could not even pull the trigger of his gun. But, who actually knows that he had a special power within him, which only Mateliya can control. This begins the adventure of the contract of the boy and his master to save others.