There are many signs in the extensive Tokyo Underground network. So many, in fact, that I find myself looking to see if anyone actually notices them, or takes heed. Signs saying ordering people to walk in certain areas rarely work, when one person ignores the sign. Then, like fish escaping a predator, everyone darts into a shoal, flowing around any obstacles (people) in the way. Well, this sign was clear. Just simply; "Keep to the left", right?