Musashi possesses a sense of fair play and he is a honorable fisherman. He always cares for mother nature like BB and Masatsugu. He couldn't think of closer friends than Mio and Suguru.

Musashi lives with his father. His mother left them three years ago. Musashi believes she will come back to them. One day they move from Tokyo to a village in the countryside. Musashi hates living in the countryside and asks his father to take him back to Tokyo. He wonders if his mother will be able to find him in their new home. 
Soon after moving to the countryside, Musashi happens to see a man fishing for bass with a decoy fish. Musashi is fascinated by lure fishing. He learns a lot from the man, and discovers that his mother's father was a grand champion of bass fishing. Musashi feels that fishing could lead him to his missing mother. He shows a marvelous talent for lure fishing and takes trips to many places around the world in search of various incredible fish. Through fishing, Musashi comes to enjoy living amongst nature. 
(Source: Official Site)

Sequel to Grander Musashi. A young but experienced fisherman named Musashi Kazama and his two friends travel around the world in search of seven mysterious objects of fantastic power called "Legenders", each one in the form of a fish. Legenders are said to grant anyone who catches them the power to change the world. Unfortunately, Musashi ends up competing with several other fishermen who share his ambition of capturing a Legender.
 
(Source: Anime News Network)