It is in a room of a girl who stays alone. One day, her friend came to visit her and stay overnight.
The room has only one single bed. So the girl sleeps on the bed, while her friend sleeps on the futon (mattress) on the floor prepared by the girl. Thereafter, both of them go to bed.
However, when the girl turned off the light in the room, her friend suddenly said,
"Oh, I suddenly feel like wanted to go to a convenience store! Let's go together."
The girl said "I am fine, you may go alone". However her friend said, "No, we must go together! Absolutely! Let's go now!" So the girl had no choice but to go to the convenience store with her friend.
Her friend’s face looks pale with sweat and running to a convenience store just like escaping from something.
The girl asked, "What happened?", and then her friend answered,
"When I lie down on the futon, I saw a man with a kitchen knife under your bed, and my eyes met his gaze just now."