Name: Mushashi
Japanese name: 武蔵
Sex: Male
Breed: Tosa

Mushashi was a great fighting dog in Shikoku. After aiding Gin in the last battle against the bear Akakabuto, he returns to the fighting arena in Shikoku. When he starts to lose the hang of it, he decides to end his career by losing to the Tosa, Toube.

Later, when Mushashi has run to Ou to help Weed, he meets Toube once more. He is very disappointed to see that the dog he chose as his follower has decided to join the evil Hougen. However, Toube makes it up to Mushashi by joining Weed and sacrifice his life to save the puppy Takeshi.

In the Hokkaido arc, Mushashi fights bravely against the Russian invader, Victor's brother Bozlef. He fights Bozlef’s soldiers to the point of exhaustion and is badly wounded. Near death, Mushashi rises once more to finish off Bozlef. However, that honor went to Moss' son Jaguar.

After the fight, Mushashi is treated for his wounds by Gin's old owner, Daisuke and the doctor, Hidetoshi. After a couple of days, he is released again into the wild, where he reunites with the Ou army.