Kewpie is building a Japanese convenience store in Covent Garden Piazza for two days, and giving away the sandwich that store is known for. The KEWPIE MAYONNAISE pop-up runs on Saturday 19 and Sunday 20 September 2026, entry is free, and the thing to turn up for is a tamago sando, the egg sandwich sold in every konbini in Japan.
The hours are different on each day. Saturday runs from 11am to 8pm and Sunday from 11am to 6pm, so Sunday closes two hours earlier. Nothing in the announcement mentions tickets or booking, so this reads as walk up and queue.
A Japanese convenience store rebuilt in the Piazza for two days, handing out the sandwich it is famous for.
What is inside the Kewpie Konbini
The space is styled as a KEWPIE KONBINI, a Japanese convenience store built for the weekend in the middle of the Piazza. What is on offer inside, according to the announcement:
- A tamago sando made with Kewpie mayonnaise, to taste there
- A limited edition Mayozine, a zine produced for the KEWPIE IT. campaign
- A chance to win Kewpie products, including a bottle of the mayonnaise to take home
- Merchandise, which the announcement lists as available to buy rather than given away
- Photo spots built into the konbini set
Worth reading the two apart: the sandwich and the zine are handed out, the merchandise is for sale, and the bottles of mayonnaise are a prize rather than a giveaway to everyone through the door.
The tamago sando, and why Kewpie mayonnaise changes it
A tamago sando is egg mayonnaise between two slices of crustless milk bread. It is one of the things people who have been to Japan talk about afterwards, and it sits in the chiller of every Japanese convenience store alongside the onigiri and the bento. The bread is softer and sweeter than a British sandwich loaf, and the filling is looser and richer than an English egg mayonnaise.
Most of that richness comes from the mayonnaise. Kewpie mayonnaise is made predominantly with egg yolks where a European mayonnaise uses whole eggs, which is where the deeper yellow colour and the heavier texture come from. Kewpie also uses its own vinegar blend rather than a standard white wine vinegar. Those two decisions are the whole difference, and they are why the sandwich does not taste the same if you make it at home with a supermarket jar.
Kewpie mayonnaise has been made since 1925
Kewpie Corporation started in 1919 as Shokuhin Kogyo Co., Ltd., making sauces. Its founder, Toichiro Nakashima, had come across mayonnaise while travelling abroad in the 1910s and was struck by how nutritious it was. He wanted a Japanese version good enough and cheap enough to become an everyday staple, and put the first Japanese made mayonnaise on sale in 1925. The company has been making it for more than a century.
The pop-up is the London launch of KEWPIE IT., a campaign built around using the mayonnaise on ordinary food rather than treating it as a speciality item, whether that is a sandwich, a salad, a burger or a plate of vegetables. Kewpie’s own account of the brand runs through the same ground at more length.
Planning your visit
The pop-up sits in Covent Garden Piazza, which is a two minute walk from Covent Garden underground station on the Piccadilly line, or about five minutes from Leicester Square. The announcement gives no more precise position than the Piazza itself, so allow a few minutes to find it once you arrive.
Saturday is the longer day and the later hours, so an evening visit is only possible on the 19th. Free food in central London on a September weekend tends to draw a queue, so the quieter windows are likely to be the first hour on Saturday morning and the middle of Sunday afternoon.
Covent Garden Piazza
Event details
- Event: KEWPIE IT., the KEWPIE MAYONNAISE tamago sando pop-up
- Dates: Saturday 19 and Sunday 20 September 2026
- Saturday hours: 11am to 8pm
- Sunday hours: 11am to 6pm
- Venue: Covent Garden Piazza, London
- Entry: free, with no ticket or booking mentioned
- Nearest station: Covent Garden on the Piccadilly line
Two days is the whole run, and there is no second London date in the announcement. If the tamago sando is the reason you are going, Saturday gives you nine hours to get there and Sunday gives you seven.
