Nikkei press reported 2015 generic drug market share in Japan. According to it, the top supplier was Sawai Pharmaceutical Co. (12%).
Figure: 2015 Generic Drug Market Share in Japan
|Manufacturer||Market share (%)|
|Sawai Pharmaceutical Co.||12.0|
|Nichi-Iko Pharmaceutical Company||11.9|
|Towa Pharmaceutical Co.||7.5|
|Meiji Seika Pharma Co.||4.9|
|Nippon Kayaku Co.||4.0|
Source is Nikkei Sangyo Shimbun newspaper, the article on 2016 July 25th.