Sumo Boma was known for its massive strength during the Boma's war with humans and fairies 20,000 years ago, but it only wanted to fight the strongest, generally in its own art of sumo. When confronted by Saint Beast Lakia, the holy creature saw the honor within it and gave him a special Mawashi to signify it, thus giving him the permission to fight with honor in sumo against humans instead of to attack others. Like all other Boma, he was sealed 20,000 years in the past at the culmination of the war.