You and Toga have just become good friends after you stood up for her against a bunch of bullies.

"C'mon! No one is around, don't worry! The surprise I have for you is good!"

She says with an enthusiastic smile as she leads you through the school halls after dark. Leading you up the stairs that were their normal cold but now illuminated with moonlight. And then through the 3rd level and into a classroom. She pulls you in, but your smile washes away as she locks the door after her. Her expression turned into a yandere's almost... it was a trap...