When it comes to Japanese retail billionaires, the first name that springs to mind might be Tadashi Yanai, the entrepreneur behind the Uniqlo brand and the nation’s richest man.

But there’s another founder who’s drawing attention as one of his biggest companies transforms in the country.

Yoshio Tsuchiya’s Workman Co. has expanded beyond its roots as a maker of drab uniforms for laborers into low-cost but functional sportswear and outdoor gear. The evolution has won praise from investors, analysts and even Fast Retailing Co.’s Yanai, who says the company has created a "new market,” although other observers question whether the positive momentum has reached its limit.