Do you know why Japanese restaurants have a button to call the waiter?

In 1985 Sasa Kozo ran a small import company in Chigasaki, a seaside town southwest of Tokyo. He came across a wireless call button called Bellstar, made by another company, and became one of its dealers. He was sure restaurants would need it.

They did not. Sakamoto Koichi, a director of the company Sasa founded, says service in those days meant staff watching the room and noticing you. A customer summoning staff with a button was, in the owners' words, "unthinkable". In the first year Sasa sold six sets, demonstration models included.

The other dealers were selling little too, and many were thinking of dropping the product. At a meeting of dealers, Town News reported, Sasa announced he would sell 100 sets the next year. Sasa says his other goods made up 98 percent of his sales, and he stopped selling them to put everything on the button.

He changed how he sold it. Instead of describing a gadget, he told owners what happens after they install one: fewer complaints, more repeat orders, fewer staff needed. He worked out a lease that cost, by his figures, about 300 yen a day for 15 tables, and a chart that let an owner see the cost at a glance. Sales climbed, and Town News says he reached the 100.

In 1993 Skylark, a large family-restaurant group, asked to put the button in every Gusto branch. The button suited late-night shifts with few staff, and other chains followed. Sasa's company, Pacific Shonan, still sells them.

• The button. At your first sit-down meal on the tour, your guide shows how it works. Press once and your table number appears on the staff's display. Press twice and, Pacific Shonan says, it flashes, which means "hurry".
• The brand. Many of the buttons you will see are Sonnet-kun, Pacific Shonan's own brand. Look for the name on the side.

• Daily Portal Z, 2023-05-15, interview with Pacific Shonan director Sakamoto Koichi
• Town News (Kanagawa), 2024-06-21
• Interview with Sasa Kozo, j-ioc