After returning from the Siberian campaign, Mitsuo Sakai established a sword business (Kokon Tozai Sword Research Institute) along with his inn business. At the time, he was mainly involved in the trading of old swords.

The Manchurian Incident and the subsequent Second Sino-Japanese War increased the demand for military swords. The sword industry was booming, and the Kokon Tozai Sword Research Institute was also engaged in sword crafts and military sword coating.

After Japan's defeat in World War II, the Occupation forces banned swords, and the sword business was discontinued.

As Japan entered a period of high economic growth, kendo became popular as the economy boomed. Traditional Japanese culture, such as swordsmanship and iaido were reevaluated. In response to this trend, Tetsushi Sakai, grandson of Mitsuo Sakai, re-established the sword business under the name of Minosaka Limited Partnership. As Mino had been a manufacturing center for military swords during the war, there were still many sword-making craftsmen left in 1973. They began to use their skills to manufacture and sell swords for iaido practice, new swords, and general weapons for display.

Today, we continue to pass on our skills in sword making, and through our sword business, also pass on the traditional beauty of Japan and the spirit of bushido forged through iaido and swordsmanship to a wide range of people both at home and abroad.