The Top Challenge League was a professional rugby union competition in Japan.

[1] For the 2003–04 season, a Top League competition was created as the top-tier competition in Japan, consisting of twelve teams.

The three teams that won the regional leagues progressed to the Challenge 1 series, while the runners-up progressed to the Challenge 2 series.

In both divisions, teams played in a round-robin format to determine the final standings.

The top teams from Challenge 2 would either qualify to the promotion play-off matches, or progress to the same season's Challenge 1 series.