Ignore it

You can't get involved. Maybe she is even enjoying this. You quickly go inside the building, you can't stay out here forever after all. Nervously you look around. At the right there a door. You see the sign that reads Janitor's Office (Do not disturb). You go a few steps farther inside and to both sides is a long corridor with lots of classroom doors. Right in front of you is a broad white staircase leading up and down. At left of the stairs are the toilets, separated by male, female and teacher.

Two female students are standing to the right of the stairs, chatting quietly. They look at you for a second and giggle, then go back to chatting. A student is leaning against the walls near the janitor's office, playing something on his smartphone. A few other students are roaming the corridor or going up and down the staircase. (Click here for the map).