(you can decide if you're human or monster. Enjoy.)

you go to the hometown school, you are in Alphys' class room with kris, susie, noelle, berdly, etc. You were finishing your work when the bell suddenly rings.

Alphys: t-that's class everyone! Time for lunch!

you and everyone else walk out and go on your way to the lunch room when you see kris and susie go to the supply closet. You hide behind the wall and see them open the closet to a dark void that they then jump into.

You are the only one who sees this but you can go tell someone or investigate yourself, or ignore it or do something else, your call.