Ginga Densetsu Riki
He hates humans and was possibly once a pet dog with bad owner, as it's been mentioned that he has suffered in his past because of humans.
When he and his pack sees Riki they attack him for being a pet dog. Riki tries to makes his escape by jumping into a river, but as he is about to drown, Shiro jumps into the river and saves Riki. . Later on as Heiji and his pack finds a passed out Daisuke. They start to attack him but Riki does his best to fight them off, and several of Heiji's ribs are broken. When Takeda Gohee and Shiro appear, Heiji and his pack flees. After that, Heiji and his pack appears only one time, when they see Riki run to see his mother.
He says he'll make Riki pay for his wounds but he never does and is never seen again.
"I kill everyone with human smell!"
- Heiji showing his hatred towards humans.Ginga Densetsu Riki
"It must be an easy life on the protection of humans!"
- Heiji taunting Riki and showing bitterness and possible jealousy towards his easy life.Ginga Densetsu Riki
"I, Mamushi Heiji, have never met a brat this annoying!"
- Heiji telling his opinion of Riki.Ginga Densetsu Riki