Magic... Does appear to be a thing. It's not properly explained in schools- The most that formal education goes to address it is a note in physics textbooks saying 'it is thought that abnormal phenomena still obey physical laws, and we simply do not understand them yet, however, studying such things tends to be difficult'. Occasionally news stories mention the Magical Girl Teams, dealing with some sort of supernatural hazard, or helping out with wildfires or floods. Or the news blames whatever random trouble is going on- Power outages, a missing teenager, a wave of drug abuse- On magic of one sort of another, usually with no actual explanation. Half the time, it turns out the explanation was mundane all along.
This is all you would really know naturally as an ordinary American teen, if you didn't deliberately seek it out: Magic is rare and mysterious, and the Magical Girls keep the public safe from it.
Today, the local team of Magical Girls is fighting some sort of darkness-themed monstrosity in a large park. A few people, too close to it, have collapsed in psychic pain. Everyone further away sees an indistinct mass of darkness or smoke, occasionally forming claws or tentacles or mouths like some sort of AI-generated fractal in a way that hurts a little bit to look at. The local three girls - Cherry Bomb, Fairy Fencer, and Velvet Maiden Vanessa - launch various glowing attacks at it until it's dead. Then the Puchuu, the colorful fluffy animal companions that seem to be in charge of the Magical Girls, go around to the people closest to the epicenter, and do something that seems to stop the pain, but also makes witnesses and bystanders look confused and dull-eyed.
Someone at the very edge of the zone might be able to witness this and not be noticed by the Puchuu.