Zack is the leader of the neighbor pack of Hidaka Reiji.
His ancestors and Hidaka Reiji's ancestors had fierce fights over territory.
Chōmon no TabiEdit
Zack was born to the pack leader with his 3 siblings. Before they were even named, the curious puppies ran to explore and were found by a human.
The human took Zack and his siblings inside his knapsack and ran. Hidaka Reiji saw this and chased the man with his minions. The scared human threw the knapsack into the river. Hidaka Reiji rescued the puppies and thus peace was created between the two packs. Zack was named after the incident.
Zack respected Hidaka Reiji a lot and eventually took over the pack as his father turned old and eventually died.
Hidaka Reiji never returned which started rumors and restlessness.
Zack's neighbor pack seemed to fell on chaos and its members were starved and tired. Some dogs were even killed. Zack believed that Shin and his brothers caused this while in reality it was all because of Muramasa.
Gin shows up with Smith and Chūtora. Zack treats them as his guests though his pack doesn't have that much food either. Zack wishes the three would join his pack to fight Shin and explains the history of the area.
After finding out that the three are Ōu's dogs and when more Ōu's soldiers come, Zack joins them to help Shin's pack get rid of Muramasa. After Muramasa was defeated, Zack became great friends with Shin and peace was restored.
See more pictures in Zack/Gallery.