It is in a room of a girl who lives alone. One day, her friend visited her and stayed overnight.
The room has only one single bed. So the girl slept on the bed, while her friend slept on the futon (mattress) on the floor prepared by the girl. Thereafter, both of them went to sleep.
However, when the girl turned off the light in the room, her friend suddenly said,
"Oh, I suddenly want to go to a convenience store! Let's go together now!"
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. We ran 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 just met his gaze..."