known as Yamaha Júbilo) Tokyo Sungoliath Toshiba Brave Lupus Tokyo Toyota Verblitz Yokohama Canon Eagles Division 2 Hanazono Kintetsu Liners Hino Red Dolphins Kamaishi Seawaves Mie Honda Heat Mitsubishi Sagamihara DynaBoars Skyactivs Hiroshima Division 3 Chugoku Red Regulions Kurita Water Gush Akishima Kyuden Voltex (without city/prefecture in the name) Munakata Sanix Blues Shimizu Koto Blue Sharks Developments 2006–07: The league was expanded from 12 to 14 teams. 2007–08: A timekeeping system independent of the referee was introduced. 2008–09: Video referee (TMO) decisions were introduced for the Microsoft Cup play-off tournament. 2008–09: Three foreign players per team are allowed on the field at one time, one more than previously. Additionally, one member of an Asian union (such as South Korean Kim Kwang Mo for Sanyo Wild Knights) is permitted to take the field for each team. 2009–10: One of the three foreign players allowed on the field must have played, or be eligible, for Japan. 2013–14: The league was expanded from 14 to 16 teams. 2014–15: Video referee (TMO) decisions introduced for all league games. 2014–15: Playoff tournament sponsored as the Lixil Cup. 2021: Japan Rugby League One announced as the new league name, starting from the 2022 season. Related competitions A second-tier Top League Challenge Series was also introduced in 2003. Between 2003–04 and 2016–17, teams from three regional leagues would qualify to this post-season competition, in which they could either win promotion to the next season's Top League, or qualify to promotion play-off matches. In 2017, a second-tier Top Challenge League was introduced, to operate in a league format above the regional leagues. The regional leagues are: Top East League, administered by the Japan East Rugby Football Union Top West League, administered by the Kansai Rugby Football Union Top Kyūshū League, administered by the Kyūshū Rugby Football Union With the creation of Rugby League One and its three divisions, the raison d'etre for the Top Challenge League ceased to exist, and it was discontinued. Seasons Sixteen teams: 2012 onwards Kintetsu Liners Kobelco Steelers Munakata Sanix Blues NTT DoCoMo Red Hurricanes NEC Green Rockets NTT Communications Shining Arcs Ricoh Black Rams Sanyo Wild Knights Suntory Sungoliath Toshiba Brave Lupus Toyota Verblitz Toyota Industries Shuttles Honda Heat Yamaha Jubilo Hino Red Dolphins Mitsubishi Dynaboars Fourteen teams: 2006 to 2012 Ninth season (2011–12) NTT Shining Arcs and Yamaha Jubilo which won their 2005 promotion/relegation play-offs (Irekaesen) against Canon Eagles and Kyuden Voltex