The founder of YKT, Keizo Yamamoto, joined the American trading company Andrew George, where he worked as sales of imported machine tools. During this time, he achieved success by delivering the first Gleason gear cutting machine in Japan to The Imperial Steel Works (a UNESCO World Heritage site: Sites of Japan's Meiji Industrial Revolution).

Gustav Rudolf, a German, became a prisoner of war during the Battle of Tsingtao in World War I and was interned at the Bando Prisoner of War Camp in Tokushima Prefecture. At the Bando Camp, he was given opportunities such as baking bread and pastries and playing musical instruments. He became an instructor in gymnastics and a member of the Engel Orchestra, forging friendships with local residents. After Germany's defeat, he remained in Japan and worked for Carting, a German trading company specializing in import of German machine tools.

Through Hahn und Kolb, two INDEX Type 0 machines were sold in Japan. The Trans-Siberian Railway was used for transporting the machines, allowing them to reach Japan in 2-3 weeks. INDEX lathes were utilized for processing diesel engine injection nozzle components for military use. When the Second World War made machine transport via the Trans-Siberian Railway difficult, modified military submarines and U-boats were used to transport INDEX machines to Japan, while alloy metals were shipped from Japan and the Pacific region to Germany. Over 900 INDEX automatic lathes were delivered in Japan, with most sold before the 1960s when Japanese-made lathes rapidly gained competitiveness, resulting in a decline in INDEX machine sales in Japan. We began handling INDEX machines since the year following our company’s founding, and we remain their sole distributor up to 2024. In 2014, INDEX celebrated its 100th anniversary, and we have been the longest-running distributor, maintaining our partnership for a century.

After the war, as the demand for precision tools declined and international trade resumed, Yamamoto Kogyo separated the import and sales of machine tools from its operations and reestablished Yamamoto Trading. Branch offices were opened in Osaka and Nagoya, resuming the import and sales of machine tools. Yamamoto Trading and its separate division, which was manufacturing precision tools in Koganei, evolved into Koganei Corporation, a comprehensive manufacturer of pneumatic and hydraulic equipment, which continues to this day (as of 2024).
On the other hand, Mr. Rudolf returned to Germany after the war and, together with his colleague Mr. Von Appen, established Von Appen & Rudolf Trading Company. Based in Hamburg, they handled exports from Germany, while Yamamoto Trading handled imports in Japan, establishing a sales route for German machine tools.

With the outbreak of the Korean War in 1950, Japan entered a period of reconstruction. At that time, domestic machine tools suffered from poor materials, leading to early wear of guideways and rapid degradation of accuracy. As a result, imported machine tools capable of maintaining superior accuracy over an extended period were in high demand. In 1952, with the government granting subsidies for imported machine tools, the sale of imported machine tools became increasingly bustling. In 1954, Yamamoto Trading exhibited an INDEX single-axis lathe at the Japan International Trade Fair, showcasing industrial products. Subsequently, this trade fair was held alternately in Osaka and Tokyo each year and evolved into a biennial specialized exhibition for machine tools. The first Japan International Machine Tool Fair (JIMTOF) was held in Osaka in 1962. Our company has been continuously exhibiting at on-site JIMTOF thanks to our customers’ support.

In the 1960s, under government subsidies, many excellent Western machine tools were imported for the purpose of imitation. Furthermore, domestic machine tool manufacturers significantly improved their performance by actively engaging in technological partnerships with advanced Western machine tool manufacturers. In 1967, Yamamoto Trading relocated its headquarters to the vicinity of Yoyogi-Hachiman Station on the Odakyu Line and changed its name to "Yamamoto Kikai Tsusho" (Yamamoto Machinery Trading). A domestic business department was established, and sales and exports of competitive domestic machine tools commenced. At that time, while there were internal discussions regarding the sales of domestic machine tools, which competed with imported ones, the following passage remains in the company guidebook:
Following the natural law of water flowing from high to low, we import high-tech measurement equipment and industrial machinery, while exporting domestic machinery with high potential energy.

Based on the belief that, despite superior machine performance, final accuracy of the workpiece depends on cutting tools, our company embarked on product development for the cutting tool industry. In order to have European machinery evaluated by domestic tool manufacturers familiar with cutting tools, the first tool tour was organized in 1981. Among the main destinations of the tour was Rollier, who was the predecessor of Rollomatic, manufacturing point grinding machines for producing microdrills. The tour at the time was summarized as follows: "In the future, convincing users to introduce the highest European technology will become increasingly difficult. Only specialized trading companies that can connect manufacturing experts with end users can handle imported machinery."

One of the destinations on the YET '81 tour was Company Rollier, the predecessor of Rollomatic, which manufactured and sold small-diameter drills and grinders. The company initially engaged in the manufacturing of watch parts but found that high-quality tools were not available on the market. This led them to manufacture small-diameter tools themselves, which gained a good reputation among industry peers. The machine they developed, called "Roll-O-Matic," was a drill point thinning grinder sold mainly in Germany and Switzerland.

At that time, Japanese cutting tool manufacturers were struggling with runout issues. They observed part-time female workers at Rollier easily producing small-diameter drills with minimal runout. The runout control of their tools was achieved through a guide bush support method with a tolerance range of a few microns. Due to the high evaluation of the Roll-O-Matic, there was a rush of requests to purchase the machines.

Initially, Rollier was reluctant to sell their machines in Japan, but gradually the path to sales in Japan was opened.

The production engineering division of Kyushu Matsushita Electric, formerly located on Minoshima Island in Fukuoka Prefecture, was a user of surface grinding machines from the German manufacturer Carl Jung Machine. On the other hand, we provided sales support for their winding machines, particularly automatic assembly devices for automobiles. With the start of surface mounter production by Kyushu Matsushita Electric, our challenge to the electronics industry began as a sales agent for mounters. With the spread of electronic products such as video games, mobile phones, CD players, and personal computers, surface mounters became high in demand. Furthermore, Kyushu Matsushita Electric's surface mounter "CREATE" boasted industry-leading high-speed and high-precision capabilities, receiving high praise from many domestic users. In the 1990s, surface mounter production shifted to Taiwan, and then to China from the 2000s onwards. During this transition, our company established subsidiaries in Taiwan and China, laying the groundwork for expansion into the Chinese-speaking region. Kyushu Matsushita Electric's FA Division was integrated with the FA Division of Matsushita Electric Industrial Co., Ltd. in 2003, and we have continued to maintain business relationships with the newly joint company under the name Panasonic Connect (as of 2024).

In 1983, we began handling video camera-type measuring machines from the American company OGP. These were very expensive products, and the concept of measuring images captured by video cameras was not yet widely recognized in the market, leading to difficulties in sales. OGP, dissatisfied with the sales figures, became increasingly concerned as sales of similar Japanese-made products began. As a condition for continuing the partnership, we were required to sell 10 units over the next year.
Two favorable conditions emerged at this point, pushing our company forward. Firstly, the introduction of the new Q-SEE series was significant. With a shift from pulse motors to servo motors, these machines enabled agile measurements and were designed with improved usability for on-site operations. At that time, the term "turbo" was popular, and the agile measurement operations of the Q-SEE series were described as "turbo". Additionally, in 1988, during the economic bubble, there was a boom in capital investment. The heightened competitiveness of the product and the flourishing market environment were fortunate factors, as sales, which had been limited to two units in 1987, skyrocketed to an astonishing 19 units in 1988. Thanks to this miracle in 1988, our partnership with OGP continued.

The construction of our own building for the Nagoya office was completed, including a showroom. We established a demonstration system for imported machine tools and measurement equipment, aiming to strengthen our sales presence in the Chubu region.

In the growing market of the telecommunications sector alongside the trend of digitization, we expanded our product range and thus subsidiarized Sun Instruments, an import trading company specializing in laser, optical communication equipment, and spectrometers.

As a joint project with Nissho Machinery, we began the development and sales of peripheral devices for display mounting machines, such as conveying devices and terminal cleaning machines. In 2009, we expanded our lineup to include display mounting machines, which have been adopted in smartphones, tablets, laptops, and automotive displays, and are sold primarily in the Chinese-speaking region.

To ensure profitability for each base, we restructured both the Nagoya and Osaka sales offices into branches. A self-owned building with a showroom was completed for the Osaka branch, with the aim of stabilizing revenue. To achieve this, half of the building was utilized as residential apartments. We also established a demonstration system for imported machine tools and measurement equipment to strengthen sales efforts in western Japan.

Since it was found to be difficult to install a showroom during the reconstruction of our headquarters building, we established a demonstration center in Fuchu instead. This facility is not only for showcasing measurement equipment but also for conducting demonstrations, providing a well-prepared environment.

We expanded the functionality of terminal cleaning machines for display mounting, as well as mounting machines compatible with OLED, LCD, and silicon panels. In addition, we started development of semiconductor mounting equipment and made a full-fledged entry into the semiconductor mounting industry