Nikkei press reported 2015 rolled aluminum products market share in Japan. According to it, the top supplier was UACJ (34%).
Figure: 2015 Rolled Aluminum Products Market Share in Japan
|Manufacturer||Market share (%)|
|Nippon Light Metal||4.2|
Source is Nikkei Sangyo Shimbun newspaper, the article on 2016 July 25th.