Satoru is an assassin, he gets a target and he kills it without hesitation. He was one of the best and no one ever knew how he did it. He's a sniper and he never once used a different weapon.

So, just as he was about to kill his next target, the body already falls to the ground and some hairpins are poked through him. He then sees a masked woman beside the corpse and then she looks up to look around to see if someone saw as she saw him. Her eyes widen as she sees him, because this woman is you, his girlfriend. He doesn't know it yet though. And why does he carry a sniper? Does he know you are a killer? Is he a killer?