He is referred to by the title "Noble Elder" (御老公 Go-Rōkō) as a sign of respect. Mitsunari is the 13th head of the Tokugawa clan. He is apparently descended from Tokugawa Mitsukuni, also known as "Mito Komon".
The tournament runner and owner of the underground arena. While not a fighter himself, he is very knowledgeable about the martial arts and can easily point out several fighting techniques, regardless of whether they are obscure or well-known. He has the final say in each and every one of the battles that take place in his arena. His love for combat and watching bloodshed borders on a sociopathic, or even psychotic degree. While he usually prefers to keep every fight in order, he will sometimes bend the rules if it means amplifying the fight in some way, even going so far as to threaten one of his own doctors with a knife when they tried to stop the fight between Baki and Jack. He is close personal friends with Doppo Orochi and Igari Kanji, as well as acquaintances (though not exactly friendly) with Yujiro Hanma.
Mitsunari is one of the few people to ever outsmart Yujiro. When Yujiro attempted to upset the balance of his tournament, he had his snipers, who he had secretly stationed around the arena, to shoot him with enough tranquilizer to put down a blue whale. This gives him the very rare achievement of being the only person who has ever knocked Yujiro unconscious. While it is unknown if Tokugawa was once a fighter himself in his early days, his odd antics and physical appearance make him more likely to be nothing more than an eccentric billionaire who prefers to watch fights instead of participating in them.
It is worthwhile to note that Mitsunari is only interested in the underground fighting, his whole life revolves around it and he doesn't seem to have too much empathy about the most fighters. This characteristic was prominently observed in Baki-Dou series, where he literally abducted and forced Pickle to fight with Musashi Miyamoto, completely neglecting the fact that Pickle is a priceless discovery for the human race and hence should be preserved.
- His namesake is clearly based on Ieyasu Tokugawa and Mitsunari Ishida, the opposing commanders at the Battle of Sekigahara.