The 2018 Top Challenge League was the second season of Japan's second-tier domestic rugby union competition, the Top Challenge League. It was played from 8 September to 9 December 2018, with eight participating teams. NTT DoCoMo Red Hurricanes won the competition for the third time – having previously won in 2010–11 and 2016–17 and qualified for the , along with Mitsubishi Sagamihara DynaBoars, Kintetsu Liners and Kurita Water Gush. Kamaishi Seawaves and Chugoku Red Regulions finished seventh and eighth respectively to qualify for the .