Responses
They could have just been talking to each other in the hall adn kept moving, or one of them could have been giving the other directions to a room or building in the school.
They are all in the same school after all, its not like you can't have contact with your fellow school mates.
Sousuke: I have someone I like.
Me: well we all know who that is. Only one question left, whos that girl that was seen with sousuke? PONYO!!! JK JK. But srsly why was he walking with her?