The Top League is a semi-professional rugby union competition which is played in Japan. The Top League is at the top of the national league system in Japan, with promotion and relegation between the Top League and the next level down. The 2009-10 season was the seventh season of the Top League since the first season in 2003-04.
Last seasons rule change of allowing three overseas players on the field at any one time was altered for the 2009-10 season, one of the three overseas players must have already represented Japan, be currently eligible to represent Japan or eligible to represent Japan in the future.
Teams are allowed to field one player from the Asian Rugby Football Union (ARFU) outside the above restrictions on overseas players. That Asian player may have represented another country at Test, A or Sevens levels as long as that country is a Union member of the ARFU.
Last season the top six finishers automatically qualified for the National Championship, however this season the top four qualify, with the teams that finish 5th to 10th playing off for the remaining two Top League qualifiers.