Winners of Japanese rugby tournaments (far from complete)

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Top League (2003-present)
Toshiba: 2004-05, 2005-06, 2006-07, 2008-09, 2009-10
Sanyo/Panasonic: 2010-11, 2013-14, 2014-15, 2015-16
Suntory: 2007-08, 2011-12, 2012-13
Kobe Steel: 2003-04

All-Japan Championship (1960-present)
Kobe Steel: 1988-89, 1989-90, 1990-91, 1991-92, 1992-93, 1993-94, 1994-95, 1999-2000, 2000-01 (shared)
Nippon Steel Kamaishi: 1976-77, 1978-79, 1979-80, 1980-81, 1981-82, 1982-83, 1983-84, 1984-85
Toshiba Fucha: 1996-97, 1997-98, 1998-99, 2003-04, 2005-06 (shared), 2006-07
Suntory: 1995-96, 2000-01 (shared), 2001-02, 2010-11, 2011-12, 2012-13
Sanyo/Panasonic: 2007-08, 2008-09, 2009-10, 2013-14, 2015-16
Waseda University: 1965-66, 1970-71, 1971-72, 1987-88
Nippon Steel Yawata: 1960-61, 1962-63, 1964-65
Kintetsu: 1966-67, 1967-68, 1974-75
Toyota Motor: 1968-69, 1977-78, 1986-87
NEC: 2002-03, 2004-05, 2005-06 (shared)
Doshisha University: 1961-62, 1963-64; Ricoh: 1972-73, 1973-74
Nippon Sport Science University: 1969-70; Meiji University: 1975-76; Keio University: 1985-86, Yamaha: 2014-15

All-Japan Company Championship (1949-2003)
Nippon Steel Yawata: 1950-51, 1951-52, 1952-53, 1954-55, 1955-56, 1958-59, 1959-60, 1960-61, 1962-63, 1963-64, 1964-65, 1965-66
Kobe Steel: 1988-89, 1989-90, 1990-91, 1991-92, 1992-93, 1993-94, 1994-95, 1999-2000, 2000-01
Nippon Steel Kamaishi: 1970-71 (shared), 1976-77, 1978-79, 1979-80, 1980-81, 1981-82, 1982-83, 1983-84, 1984-85
Kintetsu: 1953-54 (shared), 1956-57, 1957-58, 1961-62, 1966-67, 1967-68, 1969-70, 1974-75
Toyota Motor: 1968-69, 1977-78, 1985-86, 1986-87, 1998-99
Toshiba Fucha: 1987-88, 1996-97, 1997-98
Ricoh: 1970-71 (shared), 1972-73, 1973-74
Suntory: 1995-96 (shared), 2001-02, 2002-03
Mitsubishi Motors Kyoto: 1971-72, 1975-76
Kotobank: 1948-49; Mitsui Chemicals: 1949-50; Kyushu Electric Power: 1953-54 (shared)
Sanyo: 1995-96 (shared)

Kanto League Champions/Top League East
Sanyo: 1969-70, 1970-71, 1976-77, 1977-78, 1978-79, 1979-80, 1980-81, 1981-82, 1985-86, 1986-87, 1987-88, 1989-90, 1990-91, 1993-94, 1994-95, 1996-97
Suntory: 1997-98, 1999-2000, 2000-01, 2001-02
Kubota: 1995-96, 1996-97, 2011-12
IBM: 2002-03, 2004-05; Mitsubishi Sagamihara: 2005-06, 2012-13; Canon Eagles: 2009-10, 2010-11
Secom: 2003-04; Yokogawa Musashino: 2006-07; Ricoh: 2007-08; NTT Communications: 2008-09

Kansai League Champions/Top League West
Kintetsu: 1957-58, 1958-59, 1959-60, 1960-61, 1961-62, 1962-63, 1963-64, 1964-65, 1965-66, 1966-67 (shared), 1967-68, 1970-71, 1971-72, 1972-73, 1973-74, 1976-77 (shared), 1987-88, 2004-05, 2005-06, 2006-07
Kobe Steel: 1982-83 (shared), 1983-84, 1985-86, 1988-89, 1989-90, 1990-91, 1991-92, 1992-93, 1994-95 (shared), 1995-96, 1996-97, 1997-98 (shared), 2000-01 
Toyota Motor: 1969-70 (shared), 1975-76, 1976-77 (shared), 1977-78 (shared), 1978-79, 1979-80, 1980-81, 1981-82 (shared), 1982-83 (shared), 1984-85, 1994-95 (shared), 1997-98 (shared), 1998-99, 1999-2000, 2002-03
Toyota Industries: 2003-04, 2008-09, 2010-11, 2011-12
Honda: 2007-08, 2012-13
Kyoto City Hall: 1966-67 (shared), 1968-69
World Corporation: 1993-94; Yamaha Motor: 2001-02
Mitsubishi Motors Kyoto: 1969-70 (shared), 1974-75 (shared), 1977-78 (shared)
Osaka Police: 1981-82 (shared), 1982-83 (shared)

Kyushu League Champions/Top League Kyushu
Mazda: 1971-72, 1982-83, 1984-85, 1986-87, 1990-91, 1992-93, 1994-95, 1995-96, 1997-98, 2006-07, 2007-08, 2008-09
Nippon Steel Yawata: 1971-72, 1972-73, 1974-75, 1976-77, 1977-78, 1979-80
Kyushu Electric Power: 2004-05, 2005-06, 2009-10, 2010-11
Coca Cola West: 2002-03, 2011-12; Fukuoka: 2003-04, 2012-13