The Gauntlet: Hachiko first appears in this episode. He is seen in Shredder's lair, barking at Chris Bradford. When Chris goes to pet him, Hachiko bites his hand, and Shredder tells Chris that Hatchiko is not pleased with him, and neither is he. Bradford later mutates into Dogpound because of the mutagen combining with the DNA of Hachiko, because of the bite in the beginning of the episode.
Hachiko appears to be an Akita, a very popular Japanese breed. A dog of the same name and breed was immortalized with a marble statue in Tokyo and has become a national symbol of loyalty and friendship.
- Hachiko is the cause of Chris Bradford's Mutation.