[Gokudera doesn’t see anyone else, and he certainly doesn’t recognize this other person trapped in this magic space with him. He walks further into the playground and looks up as the other calls out to him before he nods.]

Probably just some other dream of mine…

[It seems like a safe place to be, so who is this guy and what is he doing here?]

Turn around and go back the way you came. You should be able to leave easily that way.