>>715497565
The prologue is a scene that happened before they were brainwashed into playing again. None of it changes anything about the Real Fiction of the game, with the sole exception of the brainwashing possibly applying to Tsumugi too.

Think of the TDR dome in the middle of the peaceful city.
Think of Makoto, someone not even in the dome and our glimpse to the world outside of it.

Kaede is Real Fiction, Hope's Peak is fictional, and so is your sex life.