Ippei is a recurring character in the Pokémon anime who first appeared in person in The Legend of the Ninja Hero!. He is the older brother of Sanpei and Nihei and hails from Ninja Village. Ippei is the strongest ninja of the village, as well as the village's current chieftain.
Ippei was first mentioned by Sanpei in A Rush of Ninja Wisdom!, and was seen only in a fantasy.
Ippei made his first physical appearance in The Legend of the Ninja Hero!, making preparations for the festival. He then welcomed Sanpei, when he returned to the village accompanied by Ash and his his friends.
While watching a Pokémon battle between Sanpei and Nihei, he analyzed the battle and later commented on Sanpei's mistakes. Later, Ippei and Nihei met Sanpei, Ash and his friends in the temple dedicated to the village's heroes. He told the group about the legend of the Pokémon that had protected the village once, when a battle between ninjas took place, and showed them the leader of the heroes, a Greninja.
When the attack on village began, Ippei sent Sanpei, Ash and his friends to protect the village's chieftain, Hanzo, while he and Nihei went to face the ninja army. After discovering that Hanzo had been captured, Ippei joined the others to hear Saizo tell about Kagetomo. After discovering Hanzo's location, Otori Mountain, everyone decide to head there and save him.

Upon arriving at Otori Mountain, Ippei and Saizo continued on towards the mountain's summit, while the others fought against Heidayu and the ninja army. At Otori Mountain's summit, Ippei personally faced Kagetomo and had a battle over title of chieftain. During the course of the battle, Hanzo saw Ippei's potential as chieftain. After a hard fought battle, Ippei managed to win, defeating Kagetomo and his ninja army.
Finally, when the festival took place, Ippei was chosen as the new chieftain of the village and got handed the Symbol of the Ninja by Hanzo, as proof of his new position. After the ceremony, Ippei bade farewell to Kagetomo and Heidayu and promised Kagetomo to look after his ninjas.
The next day he was seen again saying goodbye to Ash and his friends. After their departure he, Hanzo, Sanpei, Nihei, Saizo and Shinobu had a conversation about the mysterious power of Ash's Greninja. Ippei mentioned that, again, in the words of the legend, a Greninja had saved the village.

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