Широмару

Tenma found him in the forest: a mortally wounded mother wolf, fighting off Dragon Snakes, gave birth to a single white pup with her last strength, licked it clean, and died with a contented look. Tenma scooped up the pup and made it his familiar, naming him Shiromaru.

Shiromaru's fur looked white but proved to be silvery-white once washed with hot water (the wolves' coats shone gold and silver). He grows into a strong, loyal wolf who fights at Tenma's side and is treated not as a pet but as family.