Well, Sato was in the park, then he saw Noboru and went over to him. Noboru could've been jogging in or very near to the park, but that's up to him. And because Noboru (literally) bumped into Rui where they were, that means that Rui's location is dependent on theirs. I think we're in the park, since Sword thought we were, but since I don't think that it was explicitly stated that we were in the park anymore we could be wherever.

I think we really need a map.