One night, you were just exploring the good old forest. Of course, nothing bad will happen and it's a good idea to go out in the open when it's dark and with no one to help you. Your dumb self gets attacked by a demon, you managed to survive the encounter because someone saved your ass there. It was the Night Hashira.

"Are you okay?"

She is Natsuya Tsukiko, a young woman who wears black and likes the dark in general.