Nikkei press reported 2015 printing paper market share in Japan. According to it, the top supplier was Nippon Paper (30%).
Figure: 2015 Printing Paper Market Share in Japan
|Manufacturer||Market share (%)|
|Hokuetsu Kishu Paper||15.6|
|Mitsubishi Paper Mills||7.3|
Source is Nikkei Sangyo Shimbun newspaper, the article on 2016 July 25th.