Hayato is the son of Akame, the brother of Jinnai, Kirikaze and Tsukikage and uncle of Muu, Lara and Shirozaru.

While Gin was trying to explain to four Iga dogs, (One of which being Hayato), that his pack meant no harm towards them, (See the Iga/Koga war for more details), the group soon finds themselves under attack. A battle rages between a group of Kogas, and the slightly outnumbered Iga scouts, assisted by Gin. During the battle, one of Hayato's brothers remembered his ninja code, and to help insure the safety of his house, drags one of the Koga dogs deep down into the now flooded underground tunnel, killing himself in the process. Hayato was heartbroken, and in fear and confusion, he attempted to escape. His brother Kirikaze stopped him, and reminded him of his duty as a Ninja Dog. He was to give his life before running in fear.

"Hayato, run for 150 meters to the sun!", Kirikaze said, and he did so, as a Koga dog was in hot pursuit. Gin attempted to stop him, but to no avail. The still-upset Hayato continued to cry out for his brother; "Brother, I'm going to do it! Brother!" These were his last words before, (150 meters of running later), he tore down the pit-fall trap that the Igas had placed. He and his Koga pursuer were impailed on the large spikes below.

It seems as though his only propose was to give Gin some insight on the Ninja custom and code, and to show off Gin's ideals and morals more to the target viewers. Hayato is never mentioned again in either Manga or Anime.