Katsute100 sits at 147 Brick Lane, in the stretch between Spitalfields and the Bangladeshi restaurants, and it is open every day from eleven to eight. The shop describes the room as divided by vintage Japanese screens set against turn-of-the-century British fittings, with a tatami room in the basement that customers can reserve. It is a tea room first: you sit, you are served, and the same leaf is on the shelf by the door in packets to take away.
The list is Japanese and narrow on purpose. Three greens step up the ladder rather than sitting side by side: an organic Fukamushi Sencha Asanoka, a Kyoho Sencha four pounds above it, and an Uji Premium Gyokuro at the top. Below them a roasted hojicha is the cheapest thing in the shop, and a ginger oolong is the one outlier that is not green at all. Matcha comes as a ceremonial Karin in 30 g. Every packet is 50 g except the matcha, so the prices compare directly, which is unusual and useful.
What it does not have is black tea you can take home with a weight on the label, which in this borough matters less than it sounds: the grocery four doors down sells Indian leaf by the kilo. The house runs five sites in all, in Angel, Broadway Market, Covent Garden and Edinburgh alongside this one, and lists workshops and a wholesale programme on the same site as the shop. Come for the greens, and book the basement if you want the tea served rather than weighed.