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.
The creation of the league started in August 2004 when Niigata Albirex BB and Saitama Broncos left the Japan Basketball Association, and an interim corporation was established to form a new league shortly thereafter.