Forest of Death, underground beneath the Black Tower, Training Ground 46.
This place had originally been used for the Chunin Ninja Exams. It occupied a vast area, and after the Forest of Death came under the headquarters' jurisdiction, Hyuga Yu had remodeled it into his private training ground.
To better suit and perfectly test his own strength, Hyuga Yu had focused on reinforcing the training ground's defenses.
The training ground had been built underground. Relying on the geological structure and a large number of layered barriers, it formed a shelter capable of withstanding an attack on the level of a Tailed Beast Bomb.
In the empty center of the training ground, Hyuga Yu and Kakuzu walked in together.
At this moment, confusion hung on Kakuzu's face as he watched Hyuga Yu unfurl a black scroll and undo the Summoning Jutsu formula within it. He asked in a deep voice, "You want to cultivate the Secret Technique: Earth Grudge Fear?"
"That's right." Hyuga Yu nodded.
"Then why did you bring me here? You've already mastered the ability to create Earth Grudge Fear threads. The Secret Technique: Earth Grudge Fear shouldn't be difficult for you to cultivate."
Hyuga Yu first nodded in agreement with Kakuzu's reasoning. Then he raised his palm and showed Kakuzu the pale-blue, flame-like Earth Grudge Fear "mark" on the back of his right hand. "The Earth Grudge Fear I possess originated from you. In theory, yours and mine are connected. I can use it to control you, and conversely, you should be able to use it to control me."
"But that isn't what this old man has sensed." Kakuzu gave a cold laugh, his gaze dark as he stared at Hyuga Yu. His Earth Grudge Fear was restrained by Hyuga Yu's Tenseigan Chakra, and his life and death