Kai Shimoyama was Iga ninja and a historical person. He was Joni's high-level (jap.上忍), ninja.

He is known as the man who betrayed Iga and urged Nobukatsu Oda attack there. However, these events did not actually have absolute certainty.

Ginga Densetsu Akame

Kai Shimoyama had betrayed Iga teaming up with Nobukatsu Oda. He appeared for the first time when they meet in the woods Kihē Itō, who was looking for his son and the family ninja dogs. Kihē Cain did not know to be a traitor, but guessed that Cain katanansa in the lead up behind his back. Kihē tried to dodge, but was not fast enough, and received a blow to cover the pin. Kai killed Kihēn and then quickly left the scene. Ryōjun got Cain betrayal find out the discovery of his father's body proximity Cain hat. Kai Igasta apparently escaped, but he was caught and taken to Nobunaga Oda front.