It's also behind a bar. Right after school clubs got out. I am not terribly sure why a thirteen year old would be there, at this time of day, masquerade or not.
Also, she did actually kiss him afterwards. That was the something nice. :P
Ah, sorry for not getting the full context.
Actually, spoiler:
Would that be all right?
Edit: Osamu also doesn't go to school; reason here.