Samu is one of the seven ninja dogs serving Tesshin. In the Hokkaido arc, he and Shinbe escape from the gorge where Gin and his dogs are trapped to alert Weed. However, while Samu was able to escape, Shinbe was killed by a horde of Bozlev's soldiers. Samu also pretended to be dead when spotted by a group of Aram's soldiers and so he's able to find Weed, Rocket, Mel, Hook and Hiro as well as the reinforcement pack (which consist of strays and pet dogs) and he helps by guiding them to Hokkaidō in order to defeat Victor.

In GDW:O, Matheus takes over Koga and forces Samu, Elder, Tsukikage and Toshimitsu to jump into a waterfall. Everyone except Samu survived.