Erika knows the route to school pretty well. She walks it every day, after all. She could do it almost in her sleep, which means it's a good opportunity to get lost in her own thoughts for a while. Something new and unexpected she needs to pay attention to almost never shows up.
Does this magically fix the other students? She hopes it magically fixes the other students.
They're still on the floor, probably, but it's really hard to see anything. The mist hasn't dissipated. Then, Erika hears a distant, "Um, how do I – there!"
And the mist clears, revealing the other students still apparently unconscious – they're all breathing, at least the ones Erika can see.
"We defeated evil and saved Tokyo. Or the world. Or something. At least temporarily. I only found out about all this yesterday."
"You're Sailor Mercury! One of the five Sailor Guardians chosen to defend Earth. An evil youma was using those crystal discs to brainwash people."
Hee!
...Then: "...Should we call someone? About all... This..." She looks around at the unconscious students.
They are! A couple are even starting to stir.
"Their energy's been drained. They should recover, though it might take some of them a few days."