He is splice red Kishu Inu with off-white markings on his forehead, chest, belly, and paws.
Like his sons he is loyal to his masters, to their mission and a skilled fighter. When the Koga and Iga clans were allies as a teacher Ōzaru considered all the Kōga as his brothers in arms. He is very loving towards his mate and sons, especially when he thought they all died in the burning mansion but was relieved when they were alive and well.
Ōzaru is the leader of the Iga Ninja Dogs. He fights alongside his comrades to defeat the Kōga clan and their ganins. Ōzaru is very loyal and remains by the side of his masters, Ryōjun and Taichi. As his son, Hakutaka, begins to grow into a proper Ganin, Ōzaru accompanies him into many battles and is feared by many Kōga dogs and humans alike. Ōzaru helps the Iga clan fend off the attacking Kōga dogs by fighting their leader, Ryōga, but is distracted by Taichi who has run into a fight with an Oda Clan ninja. Whilst Ōzaru ties to defend his master, Ryōga slices his side with his blade and goes in for the kill. Both Ōzaru and Ryōga stab each other in the chest and fall to ground, mortally wounded. Ōzaru dies from his injuries shortly afterwards.