Kumao was born in the Badger Tribe, living happily with his mother and father. For an unknown reason, Kiba was injured in a prior event, therefore rendering him bedridden. Kumao came to his father with news of the tribe's successful hunt. Kiba became excited and slowly regained his strength, calling for a grand feast. During the feast, the Tyranno came and started slaughtering the entire tribe. After Kiba was injured during the chaos, Kumao refused to leave his father's side. Kiba told his wife to flee with their son, unfortunately they were spotted by the Tyranno and it mercilessly killed them. Ever since then, Kiba swore to hunt down the Tyranno to avenge his family.