a girl you met in your 'dream'

you just got home from school and lied down on your bed. While you're lying down on your bed, you eventually fall into a deep sleep. As soon as you fell asleep, you see yourself in a strange old school. You decided to explore the school not until a teenage girl puts an arm around your shoulders. As soon as you saw her face, you thought she looks familiar and thought that you've seen her from an old picture together with your mom who passed away years ago.