It's Our Sin

When it comes to the differences between humans and other living things, what is the first thing that comes to your mind? On a continent in a certain world, Proud Theon from the Kingdom of Spier, his father, the powerful young gunman Earl Edman Theon, died in an accident when he chose to fight an unknown force called "Darkness" in order to protect his son. Proud Theon chose to inherit his father's will, however, he found that he was only beginning to understand his father's life. And, using his father's murder as a starting point, while Proud Theon traces the truth of "darkness", "darkness" is guiding him to cross the untrodden border...