(Ga)Gamba: Boarding School

Before traveling to London as an exchange student, Gemma visits a science museum with her family. A rare looking spider catches her attention, deciding to get a closer look, the radioactive spider bites her neck.

Experiencing the effects such as spider tingles/spider sense or sticky hands, she ignores it and assumes it's one of the weird things she always does when she was little; those "weird" things are actually proof that she's a muggleborn or in the American term, a no-maj.