Earth Grudge Fear was a secret technique Kakuzu had seized when he defected from his village.
Of course, there was more to the story.
Takigakure had sent Kakuzu to assassinate the First Hokage, Hashirama Senju. Naturally, the assassination attempt had failed, but Hashirama Senju had not killed Kakuzu.
When Kakuzu finally managed to escape back to his village, its leaders had condemned him. In his rage, Kakuzu had seized Takigakure's secret technique-Earth Grudge Fear-and used it to slaughter the village leaders and steal their hearts.
It could be said that the secret technique Earth Grudge Fear held a past Kakuzu had no desire to remember.
So when Orochimaru spoke that name, Kakuzu flew into a fury and went straight for the kill.
Bang!
A dull impact rang out!
The exploding ball of wind unleashed terrifying power in all directions, its piercing noise echoing unbearably in their ears.
Screeech...
Sparks flew!
Hard iron sand formed a thick wall that blocked the raging gale. Kakuzu's attack had achieved nothing.
"It's all thanks to Naraku's help. Otherwise, I couldn't have perfected Impure World Reincarnation this far so quickly."
Orochimaru had been improving Impure World Reincarnation all along. He wanted the dead he summoned to wield as much power as possible, preferably while remaining firmly under his control rather than running wild.
Originally, he and Kabuto Yakushi had made very slow progress in modifying Impure World Reincarnation. But then he had experienced being cut down by Naraku, which had also damaged the souls of his arms, and he had gone to Kumogakure and conducted extensive experiments on Killer B.
Now Orochimaru possessed a profound knowledge of souls, which had indirectly accelerated his development of Impure World Reincarnation considerably.
A smile appeared on Orochimaru's cold, sinister face. With a wave of his hand, the Third