Rainy Sunday Asakusa, and you’re curious about this newcomer on the corner where Mr Nagasawa’s Uogashi sushi used to stand. The sign says Kombu no Kawahito. A seaweed shop.

It looks a little upmarket, with its subdued grey exterior.

Inside, the white loamy walls and downlights show off the merchandise. All different grades of kombu, the soup-stock essential, all harvested in Hokkaido, from Raosu, Rishiri, and Hidaka.

The highest ranked is the Raosu dashi kombu, about 3,600 yen for 180 grams.

Please, try some tororo kombu soup, says the smiling uniformed shop assistant whose name you learn is Yoko Hangai. She hands you a paper cup into which she has poured hot water over tororo kombu — tissue-thin shavings of dried sheets of kombu. It’s salty and tastes good for you. No doubt as helpful for digestion as its namesake, the slimy sticky tororo yam.

The man at the back says welcome. He is Mitsuru Kawahito. His father opened a kombu store in Mitsukoshi department store in Nihombashi about 20 years ago, but died the year before last. Mitsuru carries on and expands. This is just his second store.

It’s Day Three since the doors opened. Sales are going OK, he says. He’s surprised about 90 percent of customers are locals. But he’s just a fraction off the tourist path here. He says the top seller is the Edo Tororo kombu, which he launched for the shop opening. I called it Edo because it sounds historical, he says. Yes, like Edo-mae sushi. If I called it Tokyo Tororo it sounds like a confection.

They’re laser-cut in Hokkaido, says Kawahito, showing you pictures of other samples on his phone, a carp streamer, a Halloween-like amulet.

Next-bestsellers are these cute kombu cutouts. A cherry blossom; the characters for Happiness, Samurai, Festival, Asakusa, and so on. They’re laser-cut in Hokkaido, says Kawahito, showing you pictures of other samples on his phone, a carp streamer, a teru-teru-bozu Halloween-like amulet, as Ms Hangai puts out the original-size dried cherry blossom beside the reconstituted sample. Maybe they’d be good in soup, or as a garnish in a bento box.

It’s weird being in this building. Of course you miss Uogashi sushi – nothing will replace it. But Kawahito’s shop also fits with the street. My wife chose the outside colour, he says. It’s gentle, so old and young people will feel comfortable coming in. The white stucco on the walls is made from crushed shells, and absorbs humidity. Important in a dried goods store.

You say you like the little slot window, up the side-street around the corner. He says, That’s so people can look in and aren’t scared off by catching someone’s eye inside. That seems pretty much an Edo sensitivity too.

Kombu no Kawahito is at 1-5-3 Hanakawado, Taito-ku. Open daily, 1000–1800