Sumo is a type of competitive martial arts-sport from Japan on Earth.
In Tuvok's youth, he studied many forms of martial art, including sumo. He had followed the sport ever since. Kathryn Janeway and Chakotay were also fans of the sport.
In 2375, the three discussed the match between Kar-pek and Takashi during their competition in the 77th Emperor's Cup. (VOY: "Latent Image")