I remember reading this manga but I can't remember any of the character names nor whether it was a oneshot or not. But I remember a scene where the protagonist is trapped in a dark room with a guy and she starts to freak out because she has the fear of darkness due to an accident when she was young. She and her parents were heading to France but the train crashed and the girl was the only survivor after a couple of days just being stuck in the dark train car with her dead parents' bodies.
Thanks in advance.
