Avici Banquet, Nether Sage Art!

Yu stared at him in confusion. "Netherworld Sage Mode? What's that?"

Ubiji's teaching style matched his temperament: gentle and unhurried. Rather than explain directly, he began at the beginning. "Before that, let's go over the concepts of 'chakra' and 'Sage Art' again."

Ubiji sat down on the ground.

"First, a person's chakra is a balance between Physical Energy and Mental Energy."

Yu sat down across from him. "That's common knowledge they teach at the Ninja School."

Ubiji nodded. "The Three Sage Houses are the source of all Sage Arts. Each works by breaking the original balance, introducing Natural Energy as a new variable, and establishing a new balance."

"But in the balance created by the Dragon Cave Sage Art, Physical Energy takes the lead. In the Wet Bone Forest Sage Art, Mental Energy takes the lead. And at Mount Myoboku, Natural Energy takes the lead."

"Unrestrained Sage Art combines all three. In essence, it greatly strengthens Physical Energy and Mental Energy before bringing them into a new balance with Natural Energy. That's why it's so powerful—the amount of Natural Energy it draws in is immense!"

"But whether you practice one art or all three, traditional Sage Arts have only three variables: Physical Energy, Mental Energy, and Natural Energy!"

"The Six Paths Sage Art marks the beginning of a fundamental change. It adds a fourth variable, the power of the Ten-Tails, and builds a new balance from all four..."

With that groundwork laid, Ubiji got to the point. "Now... we can talk about Nether Sage Art!"

Yu straightened his posture and listened closely.

"Nether Sage Art was created by the Netherworld's ruler, Kushaka Uddumbara," Ubiji said. "Many years ago, after his soul arrived in the Netherworld, he discovered a remarkable power born there. It resembled Natural Energy in some ways, but