Rita's main goal is to keep close to Natsuno--to make sure he doesn't do anything too reckless and get himself in trouble, and to prevent him from doing anything that could endanger this realm if she has to. She knows it will take time for him to come around to wanting to stay here, so better not to push it just yet and make him suspicious, as much as it hurts to keep so much from him...

Oh, right, this guy's still talking as they end up in the tunnels below. "Patrolling," she answers curtly. It's such a pain to have to try and not be suspicious to either of them, but she cares far less whether or not Number 82 believes her. "In case anybody gets the bright idea to sneak around."