The curtain in the doorway: reading a noren before you walk in

A strip of cloth hangs over the doorway of a ramen counter in the late morning. It's split into panels and printed with the shop's name. It isn't there for decoration. The cloth tells you the shop is open, and when it's taken down, the shop has stopped taking guests.

Out means open, in means closed

A noren (暖簾, のれん) goes up outside when service begins and comes down at closing, often taken in by the owner. Between services, a small board on the door may read 準備中 (junbi-chū, "in preparation"), and 営業中 (eigyō-chū) means the shop is open. If the cloth is inside, folded on a stool by the door, the kitchen isn't ready for you, even if every light is on.

How to pass through

The cloth usually hangs low, around eye height, so you duck your head slightly and part the panels with one hand to go in. Regulars do it in one motion, without stopping at the threshold. It isn't a bow, although it looks like the start of one, and nobody expects more than that.

暖簾をくぐる（noren o kuguru）は、店に入るという意味でも使われる。

The phrase noren o kuguru, to pass under the noren, is everyday shorthand for walking into a shop. People use it for places they visit often and for places they're entering for the first time.

A name carried on cloth

Because the cloth carries the shop's name, it has long stood for the business itself. When a master lets an apprentice open a shop under the same name, the arrangement is called noren-wake (暖簾分け), dividing the noren. At a sento, the public bath, the cloth tells men and women apart instead: 男 marks the men's side and 女 the women's, and ゆ (yu, hot water) is often printed large across the panels.

If you arrive early and the cloth is still inside, wait nearby instead of knocking. It will go up when the broth is ready, and that's when you can walk in.