Ok, after some heavy thinking, I’ve came up with an idea for who Kiro’s dad was. It’s kind of complicated though so I’ll explain. Kiro’s father was actually Fugaku’s best friend. However, their relationship started going off track when Kiro’s father, Zai (I couldn’t think of anything) didn’t agree with with Fugaku on the Cuop D’etat planned so many years ago. He believed there was a more peaceful way to do this instead of going through such means. Once Fugaku found out about the relationship Kiro’s father had gotten into with a woman from the Mist, Fugaku believed that Zai had gotten to soft. He immediately denied Zai’s request to bring Kiro and his mother to the Leaf and instead put Zai on house arrest. Once Fugaku had found out Zai had fled to the Hidden Mist and had plans to warn the Hokage of the Cuop, Fugaku inadvertently caused Zai’s death by branding him as a rogue ninja in order for him to be captured. Instead, the Mist operatives killed Zai before he could return to the Lead.
However, it’s not like Fugaku wanted Zai dead, in fact, he regrets the way everything turned out. As for Kiro, Fugaku believed that the Mist had killed him as well and as a result, never told the other Uchiha members of his existence.
I think this helps leads into Kiro’s twisted motive of destroying the clan. Unlike his father, Kiro’s beliefs will be different and more brutal. Especially with corruption from Orochimaru and even possibly Danzo. While his father wanted the Uchiha to come to peaceful with their position, Kiro will decide that the Uchiha will always succumb to hate and should therefore be eradicated. The curse of the Uchiha will be lifted through their blood...
