Heiji is a character from the manga Ginga Densetsu Riki. He is the leader of a small pack of wild dogs (around 5-6 dogs. The only pack member's name that is said is Monta).
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 Gohei 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.
Ginga Densetsu Riki
Ginga: The Last Wars