Masaru was Shogun's underground. He was Akazaru's lead among the six macaque, whose task was to capture the dog food for Shogun.
Ginga Densetsu Weed
He attacked Weed, GB, Kyoshiro, Sasuke and Pepe. Masaru managed to intercept Pepe and went to take him away, but at that very moment Ishizaru arrived on the scene. Ishizaru attacked Masaru attacked from above the head and killed him by hitting a rock.