Casio

Kashio Seisakujo was a small subcontractor making parts such as microscope components and gears. Tadao’s brother Toshio left his job to join it, and Kazuo and Yukio followed: the company became the work of four brothers.¹

A finger-ring cigarette holder Toshio designed sold well enough to pay for work on calculators. In June 1957 the brothers put the 14-A relay calculator on sale and formed Casio Computer Co., Ltd., with their father, Shigeru Kashio, as president.¹

Casio came to watches in November 1974 with the Casiotron, choosing digital quartz because the integrated circuits it had built for calculators would carry over. Its calendar adjusted itself to the length of each month. The X-1 of 1976 added a stopwatch and world time, the start of a long line of multi-function digital watches.²

The G-Shock DW-5000C went on sale in April 1983, its case reinforced with a urethane bezel and its module suspended inside so that a knock would not reach it. Nippon.com describes how it began with an engineer’s 1981 proposal for a watch that would survive a fall, and took more than 200 prototypes; its design belongs to the story of Tool-watch engineering.^3, 6

G-Shock caught on abroad before it did at home, and by the mid-1990s had become a fashion piece for the young; Baby-G, a version for women, followed in December 1994. By August 2017 Casio had shipped 100 million G-Shocks, and in 2023 the shape of the original was registered as a three-dimensional trademark.^{3, 8, 9, 10}

Later watches carried the electronics further: a solar-powered radio-controlled watch in 2001, a G-Shock linked to a smartphone by Bluetooth in 2012, and in 2014 one that takes the time from GPS satellites as well as radio signals. In July 2025 Casio released the EDIFICE EFK-100, which it calls its first mechanical watch.^{9, 10, 11}