This study is concerned with the professional Sumo as combat sports by referring to the match, Hakuho vs. Terunofuji during the professional Sumo tournament, held at Dolphins Arena on July 18th 2021. It is natural for us Japanese to maintain the current rules of Sumo, but we must keep in mind the fact that Sumo is already international sports, so that it should be amended to harmonize with existing foreign sports rules. It is suggested that Sumo Association must have a new committee for altering the rules permanently for enhancing the improvement in quality of professional Sumo, and coping with any problem without any delay. During martial arts like professional Sumo, players must forget the relations of master and pupil, parent and child, teacher and student, friends, or lovers. The advantage α Hakuho against Terunofuji is zero until η=0.9324(14th day), and then increases to the value of α=0.035 at η=1(15th day) with increasing the normalized game length η. The match, Hakuho vs. Terunofuji have been balanced completely until the normalized game length η=0.9324(14th day), and finished at η=1 (15th day) as the result of the direct combat between the two players. The game outcome have been uncertain by 100 % until the normalized game length η=0.9324(14th day), but as the result of direct match between Hakuho vs. Terunofuji, it becomes certain at η=1(15th day). It is inferred that all of Terunofuji’s experiences and efforts are worth preserving as precious instructions for everyone in our society. In this sense, it is believed that some stories relating to Terunofuji’s life have universal value crossing the border of professional Sumo.