imagine your a school girl and your upper classmen/senpai ignores you and treats you like a child but you also think hes hot you will mostly hear it in anime unless you go to a school full of yander cosplayers.
Senpai is an honorific term in anime that is used to signify that a person is an elder, senior or upperclassmen. But in some cases, Senpai can mean a crush/lover. In Yandere Simulator, Ayano Aishi has a Senpai.