The formation of the league commenced in August 2004 with an announcement by Niigata Albirex BB and Saitama Broncos that they were withdrawing their membership of the Japan Basketball Association, and the establishment of an intermediary corporation later the same month that was tasked with forming a new league.
In August 2004, Niigata Albirex BB and Saitama Broncos declared they would no longer be part of the Japan Basketball Association. A short-lived company was then formed in the same month with the goal of establishing a new basketball league.