Tohru would have learned one very important thing: trying to return something to Kotone when she didn't want it was more difficult than she expected. The money was pressed into Kotone's hand... but it sure didn't stay there. When she got back to her previous location, it might become apparent that the itch on her neck was because something was lodged there... and Kotone herself? Nowhere to be seen. 

You could disagree with the Yakuza's principles all you wanted, but she refused to let a schoolgirl try and get by with absolutely nothing. Her father didn't really need any more employees, after all.

So, as she went to get lunch, the tall girl wondered if there was a way to help without just giving the cash away...