Saikouisen Nihon Pro Mahjong
The Saikouisen Nihon Pro Mahjong association (最高位戦日本プロ麻雀協会 Saikouisen nihon puro maajan kyoukai, informally called "Saikouisen") is a professional organization of competitive mahjong players.
Membership
As of July 2014, Saikouisen currently has 274 members.