Be careful of a strong wind

Had just a quick visit to Tokyo, sadly no time to meet any of friends.

I spotted this sign when I was about to take a down escalator at Ueno Station. Although I look out for signs whenever I use an escalator, I had never seen a sign like this until then. The picture doesn't look that fine, which is also interesting. Going down the escalator, fortunately I didn't find the wind too strong.